The Center for Ultrafast Optical Science was established six years ago and has since grown to include roughly 80 students, faculty, and associated researchers, with an annual budget of $3M, all focused on exploiting the unique opportunities afforded by ultrashort optical pulses in many fields of inquiry. When we first proposed the creation of an NSF Science and Technology Center in ultrafast optical science, we emphasized that ultrashort optical pulses offer the ultimate in both temporal resolution and peak power. Femtosecond optical pulses are the shortest controlled bursts of energy yet produced, and enable the highest laboratory peak-power densities ever generated. These two characteristics have made a large number of new fields possible, in both basic sciences and applied technology. In the original proposal, we wrote that "ultrafast optical science is an inherently interdisciplinary effort ... [requiring] the collaboration of scientists and technologists working on laser and optical physics, atomic and condensed-matter physics, chemistry, optical fibers, and electronics. The field requires all of their efforts and, in turn, rewards each with otherwise unattainable opportunities of discovery in their own fields." The remarkable growth and success of CUOS has amply demonstrated the truth of that statement. The Center now includes researchers in all of those fields, as well as in plasma physics, accelerator physics, materials science, biophysics, and medicine, all working closely with scientists developing new ultrafast laser sources and measurement techniques—in short, in a "center mode" of research. The inception of the Center coincided with the rapid development of mode-locked solid-state lasers, and much of the focus was originally on "electron-volt physics," easily observable with visible-wavelength photons, such as electronic dynamics in condensed matter. The development of chirped pulse amplifiers (CPA) at CUOS has resulted in major improvements in our ability to do electron-volt physics and chemistry. Most spectacularly, it has also given rise to an explosion in "high-field" science and technology, in which the relevant electron energies are kilo-electron-volts to even tens of million electron volts. The impact of our CPA development on both peak intensity and average power is illustrated in Figure 1. High-field laser interactions with plasmas have opened up a world of possibilities in short-wavelength generation, so that now ultrashort pulses are available from the terahertz to the exahertz region of the spectrum. It is clear that, by forming an interdisciplinary center based on applications of ultrashort-pulse lasers, CUOS has had a major impact in both science and technology.

An interdisciplinary Center environment is not only fruitful for research, but also for outreach programs such as education and technology transfer. The environment of the Center is stimulating and challenging for both undergraduate and graduate students. CUOS programs in K–12 outreach encourage researchers and graduate students to become involved with science education at critical early stages and have significant local impact. The Center places a high priority on transferring technology into the marketplace. Currently at least 26 companies interact in some form with CUOS, at least nine commercial products based on CUOS research were shown at the latest Conference on Lasers and Electro-Optics (CLEO), and several companies have spun off from the Center.

At the core of ultrafast optical science is our ability to generate, manipulate, and amplify femtosecond pulses. The motivations to do so are both scientific and technological. Indeed, this dual motivation gives rise to the structure summarizing the Center’s main themes:

The mission of the Center is to investigate that fundamental science and applied technology which "pushes the envelope" of ultrafast optics. In the following, we give some examples of how this has worked at CUOS, and then outline the major thrust areas we believe will most benefit from the center mode of research in the coming five years.

There are several frontiers in ultrafast science in which center-style research can make a major impact. One is the coupling of high temporal resolution with high spatial resolution. Semiconductor quantum structures and biological cells are two important systems in which it is necessary to image (often with subwavelength resolution) the object under study; we will therefore develop and apply novel techniques in ultrafast scanning microscopy. Another frontier is in extending ultrafast measurements to new spectral regimes. Our research in high-intensity laser-matter interactions is leading to the development of practical sources of ultrashort pulses in the uv, xuv, and x-ray regions of the spectrum. Such probes have long been anticipated for their potential to open new ground in time-domain investigations of important chemical, biological, and materials systems. It is in the next five-year period that we will be in a position to exploit the novel probes provided by high-intensity lasers for time-domain basic science.

In ultrafast technology, our principal focus has been in the field of high-speed opto-electronics. Our development of ultrafast photoconductive switching has led to many breakthroughs, including the characterization of electronic and optoelectronic devices with terahertz bandwidth, generation and control of guided-wave and freely propagating terahertz radiation, high-speed photodetectors, and the jitter-free x-ray streak camera. Our efforts in the coming years will be to apply our terahertz expertise to the problem of measuring the ultrashort xuv, x-ray, and electron pulses produced in high-field laser-matter interactions.

Due to the intrinsically interdisciplinary nature of all the work described, it is ideally performed in a center environment. We have paid special attention to focusing on those areas which will particularly benefit from collaborative, innovative, center-style research. We believe that our strong track record of breaking ground in new fields of basic science, of transferring successful technologies to the commercial sector, and of providing students with an unparalleled environment for multidisciplinary education and research, is the best argument for continued support of CUOS in the coming five years.

The Center for Ultrafast Optical Science (CUOS) is the premier laboratory in the nation for fundamental and applied research with short-pulse and high-peak-power lasers. Advances in the science and technology of ultrafast lasers at CUOS have revolutionized optical science. High-repetition-rate amplified systems invented here are now workhorses throughout the field. New phenomena, such as the production of collimated million-electron-volt electrons in laser-driven plasmas, are harbingers of a new physical regime of relativistic plasma physics. The unique opportunities provided by the lasers at CUOS have generated a broad interdisciplinary science research program, encompassing condensed-matter, atomic, plasma, and beam physics; chemistry; electrical engineering; and eye surgery. In the next five years, we plan to focus on the coupling of spatial and temporal resolution as well as the generation, detection, and application of high-energy photons and electrons in condensed matter, surface physics, biology, and medical science. Research is closely connected to vigorous outreach, education, and technology transfer programs that are affecting the K–12 education system and the economic environment, with the creation of more than 50 industrial jobs.

One of the major contributions of the Center over the course of its 6-year history has been the development of high-power ultrashort-pulse amplifiers. As is by now well-known, the principal concept underlying all the amplifiers developed at CUOS is chirped pulse amplification (CPA), in which a pulse is stretched before amplification in order to minimize the peak power of the pulse in the amplifier. This allows the energy fluence in the amplifier to approach the saturation fluence, enabling efficient extraction of the energy stored in the amplifier, without deleterious high-peak-power effects such as self-phase modulation, self-focusing, or damage. After amplification, the pulse is recompressed using a simple grating pair. This technique makes it possible to generate peak power in excess of what can be accomplished using any other technique.

CPA has also made possible a revolution in high-repetition-rate amplifiers for ultrafast applications requiring pulse energies in the microjoule to millijoule range. These applications include time-resolved spectroscopy using femtosecond white-light continuum, nonlinear optics, short-wavelength generation, and micromachining; in short, a substantial portion of what is considered "ultrafast science." Prior to the development of CPA solid-state amplifiers, organic-dye laser amplifiers were typically used in this energy range. As shown in Fig. 1 (courtesy of W. H. Knox, Lucent Technologies), dye amplifiers typically operate with average power in the 10-mW range. With the advent of solid-state CPA amplifiers, average powers of 1 W or higher are routinely obtained. This two-orders-of-magnitude improvement makes it possible to perform experiments with a vastly improved signal-to-noise ratio. As a result, essentially all new systems implemented in the past four years at the hundreds of laboratories worldwide devoted to ultrafast science in the microjoule to millijoule range use the CPA solid-state regenerative amplifiers first developed at CUOS.

The impact of the multi-kilohertz amplifiers has been enormously extended in the past two years with the development of optical parametric amplifiers (OPAs) using the Ti:sapphire regenerative amplifiers as pump sources. For example, we have built a 250-kHz OPA producing sub-30-fs pulses tunable across the entire visible spectrum [Sosnowski 1995]. As a result, 100-fs amplified pulses tunable from roughly 230 nm to 10 µm are now available from kilohertz to nearly megahertz rates. Thus one of the main challenges of ultrafast optical spectroscopy has been basically solved, namely, the need for ultrashort pulses tunable from the ultraviolet to the infrared, at repetition rates and average powers sufficient to do extensive signal averaging. Of course, the revolution continues: further development of solid-state CPA amplifiers will make femtosecond pulses in new wavelength regions available, with even higher average power and shorter pulse duration, in more compact and practical configurations.

We have taken advantage of the recent advances in laser pulse-shaping technology [Weiner 1992] to control the phase of both plasma waves and electrons in the linear regime, where the laser pulse duration is equal to or less than a plasma period, and thus the aforementioned instabilities are "frozen" out. This has permitted us to engineer a whole new class of electron accelerators based on shaped-laser-pulse-driven plasma waves. One example is a laser-driven plasma cathode injector. We have shown that ultrashort-duration (10-fs) electron bunches can be injected in a wakefield by using a second laser pulse either to dephase plasma-wave electrons or to create new ones by further ionizing the medium [Umstadter 1996A]. With this technique, the electron energy spread could be reduced to only a few percent, as compared with 100% as in our present experiments; additionally, a single ultrashort electron bunch can be accelerated. The basic idea is that if a variably delayed injection pulse is brought to a focus at the correct point in space and time, it changes the trajectories of background electrons (oscillating in the plasma wave) such that they can become accelerated and trapped by the plasma wave. Employing optical techniques and plasma waves for the generation as well as the acceleration of electrons makes phase synchronization and spatial overlap much easier. Beam emittance is improved by having a much higher field gradient in the first acceleration stage. Combining this technique with that for coherent undulator radiation may ultimately provide a route to achieving attosecond pulses of x rays with a tabletop device.

Another example is a novel method for resonantly driving nonlinear plasma waves for the purpose of high-field-gradient electron acceleration, developed by us in collaboration with T. Neubert of U-M Space Physics Research Laboratory and E. Esarey from the Naval Research Laboratory. A plasma wave can be most effectively driven by a train of intense laser pulses in which the pulse widths and interpulse spacings are optimized such that resonance with the changing nonlinear plasma wavelength is maintained [Umstadter 1994, Umstadter 1995]. The power requirement of the laser can be reduced by over an order of magnitude by use of such an optimized laser pulse train. In collaboration with A. Migus from Ecole Polytechnique, preliminary results on the amplification of the required pulse trains have already been obtained [Liu 1995]. We plan to build a 1-GeV-energy laser accelerator based on these developments, but have written a separate proposal to do so since this project would otherwise require too great a fraction of the Center’s resources.

We owe our success thus far on this frontier of physics research primarily to the availability of the state-of-the-art research tools at CUOS. Accordingly, Profs. H. Kapteyn , M. Murnane, G. Mourou and D. Umstadter are planning to study the above-mentioned concepts with one of the next generation of CPA lasers, a 10-Hz, high-power (multi-terawatt), 10–15-fs laser, which is now under construction. We currently have a fully relativistic two-dimensional particle-in-cell (PIC) code in operation that numerically simulates these laser-plasma interactions on a parallel computer, and are now working on a 3-D version of it. Its further development will complement the planned experiments and provide a vehicle with which to continue to test new theoretical ideas. Through the Fellows Program, CUOS is currently expanding the collaboration nationally. For instance, Prof. M. Downer, on sabbatical at CUOS from the University of Texas, Austin, is currently using Thomson scattering to map the temporal evolution of the plasma wakefield. S. Derbenev is now providing theoretical support. R. Gustafson, a U-M research scientist, along with R. Ent and his colleagues, from Hampton University and CEBAF, are implementing electron diagnostics. Clearly, such a diversity of talent working in a single area of basic science is only available at an STC.

In the future, we propose in the near term to continue our investigation of nonlinear optics with relativistic plasmas at even higher laser intensities and higher plasma densities. Raman scattering, relativistic self-focusing and electron cavitation will be studied systematically over a wider range of parameters. Other plasma instabilities such as laser hosing, modulational instabilities, and relativistic self-phase modulation will also be investigated. We discuss in detail, in Sec. III.B.4, our longer range plans to study relativistic harmonic generation, propagation in overdense plasmas, nonlinear Thomson scattering, electron-positron plasmas, and gigagauss magnetic fields. This work will be complemented by our numerical simulation capabilities discussed above. It is difficult to say what we will be doing five years from now. This is such an active field for theorists, with new ideas for experiments being published in Physical Review Letters every month and, as with all experimentation on the frontier, we can also expect some unanticipated discoveries in the laboratory.

Over the past few years we have undertaken a rigorous study of the damage threshold in dielectrics as function of the pulse duration. This study was carried out over five orders of magnitude from 5 ns to 50 fs. It revealed that, for pulses in the picosecond range and below [see Fig. 4], the damage threshold becomes precisely determined with an accuracy better than 10% [Du 1994A]. This strongly departs from the damage threshold behavior with long pulses, which require larger fluences and where the damage fluence has a large uncertainty. This general trend was confirmed later by Stuart [Stuart 1995]. We explained this profound difference as follows. For pulses down to 50 fs the damage mechanism is dominated by avalanche ionization. In a long pulse, the avalanche is seeded from a small background of free electrons caused by defects, the density of which can vary within the laser spot size from shot to shot. The electrons are then multiplied at a rate that is, for a long pulse, extremely field dependent. As a consequence, there is a large pulse-to-pulse variation. On the other hand, for ultrashort pulses, the field is very high, so the seed electrons are produced in a deterministic way by multiphoton ionization in the rising edge of the pulse. They are then multiplied by impact ionization, which, for very large fields, saturates and is reasonably independent of field.

The low and precisely determined damage threshold of femtosecond pulses leads to a number of new possible applications [see Patent Application #939: "Subwavelength micromachining by ultrafast laser ablation," in Appendix E.2]. For instance, materials can be ablated with feature size about one tenth the spot size. Also, voids can be created in bulk transparent substrates with a dimension corresponding to a fraction of the Rayleigh range. Femtosecond ablation will lead to new applications, such as in micromachining, optical storage, dry etching and medicine.

We at CUOS immediately realized the importance of application for the low, accurate damage threshold of femtosecond lasers: in eye surgery [Du 1994B]. Since the eye is a transparent dielectric, femtosecond pulses can ablate materials independently at the surface or within the cornea, aqueous humor, lens, vitreous humor, retina and sclera. The process is independent of wavelength and the pulse duration can be continuously adjusted for optimum performance to take into account nonlinear propagation effects. A research program between U-M’s Kellogg Eye Center and CUOS has been established, with the financial backing of the university’s Office of the Vice President for Research (OVPR), in order to exploit this unique opportunity.

While lasers operating in the nanosecond regime are now used for ocular surgical procedures, they have severe limitations, including high fluence thresholds for consistent tissue ablation. Ablations within the transparent structures of the eye (such as the cornea, lens, vitreous, and retina) should be possible without extensive collateral tissue damage using low-fluence, highly accurate ablations at ultrashort pulse widths. Tissue studies performed in collaboration with Kellogg researchers confirmed that damage behavior for tissue is analogous to our findings with inorganic dielectrics. Maximal ablation efficiency was identified for pulse widths below 1 ps and fluences slightly above plasma thresholds. Additional findings revealed significantly reduced shock-wave propagation in biological tissues for ultrashort pulse widths compared with longer pulse widths. These results provided the basis for exploring laser-tissue interactions in live animals and testing the hypothesis that ablation with ultrashort pulses would result in less collateral tissue damage. In addition, they provided a first order approximation for the output requirements for a femtosecond medical laser.

We have developed animal model systems to identify key laser parameters which determine the tissue injury response. Our studies, which support the notion that ultrashort pulses produce more limited effects, are the first to evaluate the role of pulse duration in terms of immediate and long-term wound healing responses. Surgical procedures to treat glaucoma and other blinding diseases are now being evaluated in animals, using the optimal laser parameters identified in these models. The requirement for laser pulse delivery into the eye has also stimulated basic work in nonlinear pulse propagation. Characterization of self-focusing effects in liquids and the development of models that explain the behavior of ultrashort pulses are being used to predict potential limitations for surgical delivery systems.

The eye may also offer the first opportunity for a clinical application of gene therapy and ultrafast laser technology could speed this effort considerably. A major limitation to progress has been the relative inefficiency in the transfer of genes into host cells (transfection). Since ultrashort pulses can cause ablations with feature sizes of about one-tenth the spot size, micro-puncture of individual cells is possible. A cellular surgery model is being developed with the potential to greatly increase transfection efficiency. In addition, since laser-mediated transfection can be performed in the living eye, this method may revolutionize methods that now require harvesting cells, growing them in incubators, and then re-transplanting transformed cells back to the host.

Our understanding of plasma-mediated events in the subpicosecond regime has opened entire new research areas in unrelated fields. These new efforts are leading to novel applications that could have dramatic impacts in clinical medicine and biology. In turn, these applications are further stimulating both basic and applied research in ultrafast science. We plan to expand these collaborations over the next five years and anticipate our progress will lead to commercial technologies. Several patents have been applied for through U-M’s Technology Management Office (TMO), with favorable office actions already received on a key medical applications disclosure. Negotiations with several ophthalmic equipment companies are in progress to further exploit this technology.

III. A. 2. Summary of Achievements: Ultrafast Optics

The most prominent achievement of CUOS in ultrafast optics has been the development of ultrafast lasers with high peak and average power [Salin 1991, Norris 1992], as described in Sec. III.A.1.a. These sources have revolutionized time-domain studies. Moreover, CUOS optics research has made significant progress in a number of areas. Ultrafast optical pulses are "sculpted" light—optical wave forms with a precise amplitude and phase relationship over a broad frequency bandwidth. To generate high intensity also requires high spatial coherence across a beam phase front. To generate, manipulate, or amplify an ultrashort pulse thus requires total phase control, in both the time and the space dimensions. This has been the goal of the work at CUOS.

For example, the CPA process itself is simply a manipulation of the temporal phase of a pulse to stretch it in time. The ideal CPA system would stretch an ~10-fs pulse to many nanoseconds, amplify it, and recompress it to high intensity with a minimum amount of "pre-pulse" light. These requirements are mutually contradictory, and further progress in developing small-scale, high-intensity lasers requires the development of new types of phase conjugate stretcher/ compressor systems. Over the past three years, we have demonstrated new stretcher/compressor designs based on mismatched gratings [Kane 1996] and on combinations of prisms and gratings [Kane 1994], which correct for higher order phase and are suitable for pulses of 10-20 fs duration. We have also done careful analyses of the effect of nonlinear phase modulation in high-power amplification, and have developed strategies for reducing its adverse affects [Kane 1996].

To generate a high peak intensity also requires diffraction-limited focusing of the output beam, which can be problematic in lasers with high thermal load or large optical aperture. The Center has worked with a commercial firm to develop an adaptive optics element based on liquid crystals [Baur 1995] that can be used to correct for static wave-front distortions in an amplifier. This device is small and relatively inexpensive and is now also being used for astronomy.

Spatial phase control can also be translated into temporal phase control to perform pulse shaping [Weiner 1988, Weiner 1992]. Shaped pulses and pulse sequences are useful in a number of applications, including coherent control of chemical reactions and the manipulation of quantum wave functions, and for possible application in laser electron acceleration [Umstadter 1995]. Work at the Center has demonstrated that pulse shaping can be combined with CPA to produce shaped pulses at the 100-mJ level [Pinkos 1994] for use in atomic physics experiments. Precise phase control and pulse shaping also require precise phase characterization. The Center has developed a new type of temporal phase analyzer [Rhee 1996] that can work in real time so that pulse shape can be monitored as a laser is adjusted.

The CPA concept , first developed for tabletop lasers, also has important applications in fiber optics. In fact, in fiber amplifiers nonlinear distortion in short-pulse amplification can occur at very modest pulse energy, and CPA can be very useful to ameliorate these effects. We have shown that it is possible to amplify ultrashort pulses to the 1-µJ level in Er [Stock 1994], in Yb [Walton 1996], and in upconversion fibers amplifiers [Yang 1995]. The resulting high-peak-power, ultracompact lasers have many possible practical applications in ultrafast spectroscopy, surgery, imaging, micromachining, and high-power photoconductive switching.

Although not then supported by the Center, the past work of Profs. Margaret Murnane and Henry Kapteyn, who joined CUOS in January 1996 from Washington State University, has also had a very significant impact on the field of ultrafast phenomena. This work was primarily NSF-funded. Their research in ultrafast lasers resulted in the first reliable and routinely usable 10-fs pulsed laser [Asaki 1993, Zhou 1994B]. This accomplishment required the development of a detailed understanding of the operation of the mode-locked Ti:sapphire laser [Christov 1995]. Their laser design has been duplicated in hundreds of laboratories worldwide doing research in all areas of ultrafast phenomena. They also developed the technology for high-peak-power CPA amplification of 10–20-fs duration pulses [Zhou 1994A, Zhou 1995]. These lasers make it possible to generate several-terawatt peak power using a small-scale laser, and also to explore a new regime in strong-field interactions where the intensity of the laser field incident on an atom rises significantly (25%) in a single optical cycle. Most recently, they used this effect to demonstrate substantial improvements in soft-x-ray high harmonic generation [Zhou 1996]. They have also demonstrated newly developed pulse characterization techniques with 10–20-fs pulses, making it possible to characterize light pulses on a cycle-by-cycle basis, as shown in Fig. 5 [Taft 1995]. In joining the Center, they brought several state-of-the-art laser systems and ongoing experiments to Michigan, which will be upgraded as part of our effort to reach higher laser intensities. They were also accompanied by six graduate students and two postdoctoral researchers.

III. A. 3. Summary of Achievements: Ultrafast Science

Techniques for performing time-domain optical experiments in the visible and near-infrared regions of the spectrum have matured in recent years due to the tremendous advances in solid-state femtosecond lasers. (Many of the achievements and contributions of CUOS to ultrafast spectroscopy based on these advances have been described in recent annual reports.) The emphasis at the Center in ultrafast science has thus shifted to new frontiers: the application of ultrashort pulses in new wavelength regimes and the coupling of ultrafast with high-spatial-resolution techniques for basic science.

• Time-Resolved Microscopy. Two general systems in which optical probes are particularly powerful, namely semiconductor structures and biological cells, have an important feature in common: in both cases, the spatial scale of many important features is submicron. Generally, up to now, few ultrafast optical experiments have been performed in conjunction with spatial imaging, and as a matter of course "far-field" geometries with spatial resolutions of at best about a micron are used. One of the central goals of the CUOS ultrafast science program is to develop and apply new techniques coupling ultrashort laser pulses to microscopy to enable simultaneously high spatial and temporal resolution. Furthermore, it also turns out that ultrashort pulses can sometimes enable new imaging techniques as well. There are three principal approaches being taken at CUOS for simultaneously high spatial and temporal resolution: confocal and near-field microscopy for ultrafast optical measurements, and an atomic-force photoconductive nanoprobe for ultrafast electrical measurements.

• Confocal Microscopy. Confocal fluorescence microscopy has become one of the most powerful tools for the optical imaging of biological material, due to its ability to "section" and thus to generate a three-dimensional image of a sample [Brakenhoff 1979]. In traditional confocal microscopy, the sectioning is obtained using an aperture confocal to the diffraction-limited excitation. Alternatively, the sectioning may be obtained using two-photon excitation with femtosecond pulses [Denk 1990], which has a number of important advantages. At CUOS, we demonstrated a system utilizing high-repetition-rate (250-kHz), amplified femtosecond pulses to perform confocal microscopy using a line instead of point focus, and thus to perform two-photon confocal microscopy in real time, as shown in Fig. 6 [Squier 1994]. This work benefited tremendously from a collaboration between our ultrafast science and optics groups (Norris, Squier) and a Visiting Fellow (Brakenhoff), and from an industrial collaboration with Meridian Instruments.

• Near-Field Scanning Optical Microscopy (NSOM). Several Center participants have made significant contributions to the development of ultrafast measurement techniques and to their application to physics of excitons and free carriers in semiconductors (as discussed, for example, in previous CUOS annual reports). The next frontier in ultrafast semiconductor physics is to be able to perform time-resolved experiments with spatial resolution comparable to the scale of the structures under study. One of the principal themes of semiconductor device development over the past decade has been the shrinking of device dimensions, both for the increased functionality and the higher speed expected to result. The relevant time scales for electronic processes such as relaxation and transport in ultra-submicron or "mesoscopic" semiconductor structures is picoseconds to femtoseconds. Therefore, over the past few years, CUOS participants have been adapting NSOM techniques [Betzig 1991] to perform time-resolved optical spectroscopy of mesoscopic semiconductors [Smith 1995]. This work has been an interdisciplinary effort involving CUOS participants in ultrafast optics and semiconductor physics (Norris, Merlin, Steel) and in NSOM technology (Kopelman and Orr). We have demonstrated simultaneous 100-nm 100-fs resolution, and initial work on tip-sample interactions with bulk semiconductors has been performed, including characterization of the reduction of depth-of-field in nonlinear NSOM experiments, and the observation of carrier transport effects. An example of an ultrafast NSOM image is given in Fig. 7.

• Time-Resolved Studies with Terahertz (Far-Infrared) Pulses. Terahertz radiation can be produced using photoconductive switching or optical rectification in the form of unipolar subpicosecond "half-cycle" electric field pulses, shaped pulses, narrowband radiation, or guided electromagnetic waves in transmission line structures. Terahertz radiation has unique properties in material systems, since this frequency range can directly drive vibrations in molecules or phonon modes in condensed systems, and the time scale is comparable or shorter than classical orbit times of Rydberg atoms. CUOS researchers have made fundamental contributions to terahertz science and engineering over the past decade, including generation and measurement of both free-space and guided-wave single-cycle terahertz pulses, application of terahertz pulses to the investigation of semiconductor transport and high-speed device physics, and far-infrared spectroscopy of materials such as high-critical-temperature superconductors. (These accomplishments have been described in detail in previous annual reports.) Most recently, we have successfully applied high-field terahertz radiation to both probe and manipulate quantum wave functions in Rydberg atoms [Raman 1996, Reinhold 1995]. The latter work was especially facilitated by the CUOS Fellows Program; a number of groups worldwide have subsequently adopted intense terahertz pulses for atomic physics investigations following the lead of pioneering efforts through Center-funded collaborations.

III. A. 4. Summary of Achievements: Ultrafast Technology

Investigations in ultrafast technology have essentially concentrated on the development and understanding of technologies for high-speed optoelectronics in a regime that extends to terahertz frequencies. Work has progressed on a complete range of issues related to ultrashort electrical pulses, including generation, guided propagation, and measurement.

• Ultrafast Photoconductive Switching. We have extensively investigated issues relating to ultrahigh-speed photoconductive switching and gating in materials exhibiting both long relaxation times and ultrafast trapping times. Included in this effort are the most comprehensive studies to date of subpicosecond-resolution photoconductive switching and trapping in nonstoichiometric GaAs (LT-GaAs) [Liliental-Weber, 1993], the investigation of passivated Cr:GaAs photoswitches, and the intensity and bias dependencies of the pulse response of LT-GaAs interdigitated metal-semiconductor-metal detectors. The latter work has shown that high bias or peak intensity could significantly reduce the bandwidth of high-speed photodetectors.

• Jitter-Free, Picosecond Streak Camera. We have developed an averaging, picosecond, x-ray streak camera using a dc-biased photoconductive GaAs switch to generate a high-voltage ramp for the deflection plates [Maksimchuk 1996]. The streak camera is operated at a sweep speed of up to 8 ps/mm, with shot-to-shot jitter of less than 1 ps. It has been used to measure the time history of broadband and spectrally resolved x-ray emission at a 10-Hz repetition rate from an ultrashort-pulse-laser-produced plasma. Accumulation of the streaked x-ray signals significantly improved the signal-to-noise ratio of the data obtained and permitted experiments with relatively low x-ray yield to be performed [Nantel 1996]. This work represents the beginning of what should be a fruitful collaboration between the terahertz technology group (Whitaker) and the high-field laser-plasma group (Mourou, Umstadter, Maksimchuk, Nantel).

III. A. 5. Summary of Achievements: High-Field Science and High-Field Technology

• Materials Science. Accomplishments in materials science using ultrafast lasers have included the fabrication of diamond-like carbon films of excellent quality and physical properties [Qian 1995]. The laser intensities needed to produce optimum films have been identified, and comparisons to other methods of synthesis have been completed. In the course of doing this work, we have identified a new arena of research involving the creation of high energy-ions. We have performed studies on ions in the kilo-electron-volt energy-range and work is under way to establish a source of million-electron-volt ions. In addition, as part of the process of producing energetic laser ablation plumes, the mechanisms of energy absorption, redistribution, and surface damage in absorbing materials have been defined, modeled, and understood in terms of various excitation mechanisms, including linear, multiphoton, avalanche, and tunneling ionization. The avalanche ionization mechanism has been examined and is understood in greatest detail.

• Picosecond xuv Continuum Source. We have demonstrated experimentally a novel, controllable, ultrafast broadband radiation source in the extreme ultraviolet [Workman 1995], which will be useful for time-resolved dynamical studies in ultrafast science. Fig. 8 shows time-resolved spectra of an ionized gold plasma, taken with a streak camera coupled to a grazing-incidence spectrometer, under three different laser-intensity conditions. It can be seen that the x-ray pulse width can be arbitrarily adjusted by simply adjusting a single parameter (I), and thus the peak temperature of the plasma. A simple analytical model and a computer model of the laser-plasma interaction were both found to predict this same behavior [Workman 1996]. The source has already been used to measure, with picosecond time resolution, the absorption-edge shift of a thin metal film that was heated by a synchronized laser pulse [Nantel 1996].

• High Harmonic Generation. Using a novel vacuum ultraviolet ellipsometer, we have measured the polarization of high harmonics of 785-nm Ti:sapphire radiation generated in argon and nitrogen gas. When the driving field is elliptically polarized, there is generally an offset angle between the major axis of the driving field’s polarization ellipse and the polarization of the harmonics [Weihe 1995, Weihe 1996]. The ellipticity of the harmonic polarization is also generally different from that of the driving field. There are substantial differences in behavior between the two gases, particularly for harmonics whose energies lie close to the ionization potential. This behavior is contrary to simple perturbation theory predictions, but may be in accord with wave-packet scattering models for the process. We also discovered an increase in conversion efficiency of soft-x-ray harmonic generation by over an order of magnitude by using 20-fs pulses. The nonadiabatic response of atoms to intense fields was also investigated [Zhou 1996, Christov 1996].

• Strong-Field Coherent Control. We studied ATI (above-threshold ionization) in krypton and xenon with special pulses formed by superposing equal intensities of 1.06-µm and 532-nm laser light, where the relative phase between the two can be precisely controlled [Schumacher 1994]. The results show explicitly the relationship between the energy gained by a free electron born in a laser field and the phase of the field in which it is born. Our results show for the first time that these new wave-packet models of ATI are essentially correct, but that they must also take into account secondary scattering of the ionized wave packet from the parent ion core.

The goals of the ultrafast optics research program at CUOS are twofold: (1) to develop fundamental knowledge and new capabilities to generate, manipulate, and characterize light pulses, and for measurement of ultrafast processes, and (2) to drive forward the high-field science program with the continuing development of state-of-the-art laser systems. Both of these goals are well-suited to the CUOS environment, but for different reasons. Advance in fundamental ultrafast optics relies on a diverse and intellectually stimulating environment where new ideas are constantly discussed and refined. For the high-peak-power work, the required lasers are large and complex enough to require the resources and facilities of a center. However, in practice, these two research activities are closely linked. The people involved in this work are principally Kapteyn, Mourou, Murnane, and Nees.

• Ultrashort-Pulse Lasers and Measurement Techniques. Further progress in the generation and manipulation of ultrashort light pulses, especially sub-10-fs light pulses, will require a much more sophisticated understanding of and control over light propagation than has been necessary in the past. For example, in the mode-locked laser itself, beam propagation can no longer be described in the slowly varying amplitude approximation, and the possibility of finite response times, even for atomic interactions and electronic nonlinearities, must be considered. In past work we developed numerical models which couple the spatial, temporal, and nonlinear effects at the focus of the short pulse in the laser [Christov 1995]. The understanding derived from these models suggests that new technologies, resembling diffractive-optic and adaptive-optic techniques (except for temporal control rather than for wave-front control) will be necessary [Christov 1993]. We will be attempting to incorporate these techniques into femtosecond mode-locked lasers in 1997–99.

Closely coupled to this work is the development of new measurement techniques which make it possible to characterize light pulses on a cycle-by-cycle basis, and promise to make it possible to observe fast processes with subfemtosecond resolution. We demonstrated that the technique of frequency-resolved optical gating (FROG) [Kane 1993] can be used to measure the complete wave form (amplitude and phase) of a 13-fs optical pulse, as shown in Fig. 5 [Taft 1995]. This work was crucial in verifying theoretical models of the operation and fundamental limits of ultrashort-pulse solid-state lasers. Further work (1996–97) will push the limits of measurement technology, as well as shedding light on physics relevant to ultrashort-laser pulse propagation and generation. We plan (1996–98) to study phenomena such as the nonlinear response of electrons in a material to light, and to improve on extracavity pulse-compression techniques for 5–10-fs pulse generation. This work, in addition to its fundamental interest and our interest in pulse generation, has a number of applications of practical importance. These include (1) soliton propagation in optical fibers, and the limiting rate of information transmission in optical communication systems; (2) optical switching and bistability for optical computing and communications; (3) phase conjugation; (4) the design of more efficient femtosecond lasers and nonlinear frequency conversion techniques; (5) optical imaging through scattering media; (6) the generation of ultrashort-pulse x-ray and vuv light; and (7) novel laser-based particle accelerator schemes.

• Ultrashort-Pulse Amplifiers. The high-field science program, and especially projects such as laser-based accelerators and coherent x-ray sources, depend on the continued advancement of ultrashort-pulse laser technology. Currently, the terawatt-class lasers at CUOS include a high-pulse-energy Nd:glass-based laser system, and two 10-Hz Ti:sapphire-based laser systems. The Nd:glass system has been reliably in use for experiments which require joule-level pulse energies. Any expansion of this laser system would be too large-scale a project, and not feasible within the current budget of CUOS. However, the size of a laser system depends almost solely on its pulse energy, and not its peak power. Thus, there is considerable room for improvement in obtaining high peak power, by using ultrashort-pulse 10–20-fs laser systems based on Ti:sapphire laser material. Further in the future, but still within the time frame of this proposal, are the development of compact high-peak-power lasers based on high-energy-storage-density materials such as Yb:glass.

In the intermediate term (1996–98) we will be exploring new techniques to generate laser pulses with little pre-pulse energy and a fast rising edge. In the current design, the use of very broad-bandwidth optical components and compensation of high-order phase allow the generation of pulses with good peak-to-background contrast. However, to obtain a contrast suitable for solid-interaction experiments will likely require "cleaning" the pulse at an intermediate energy (~ 1 mJ). It should also be possible at this energy level to use nonlinear techniques to ameliorate gain-narrowing limitations and to generate pulses of ~ 10-fs duration [Nisoli 1996]. Also, the increasing sophistication of many of the applications, such as xuv harmonic generation and laser-based accelerators [Umstadter 1994], require specially shaped pulses and precise control of the amplitude and phase of ultrabroad-bandwidth pulses [Weiner 1988, Hillegas 1995, Weiner 1990]. We are working (1996–98) to implement ultrafast-pulse-shaping techniques into high-energy amplifier systems. These pulse-shaping techniques can also allow us to correct phase aberrations in the pulse. However, there are open questions regarding nonlinear distortion of shaped pulses in CPA systems [Pinkos 1994, Schumacher 1995, Liu 1995], which must be better understood. We will be using a high-repetition-rate 20-fs amplifier system [Backus 1995] as the test bed for ideas in these areas.

• Confocal Microscopy. In the course of our work on confocal microscopy, it has become clear that the utility of femtosecond confocal microscopy could extend far beyond simple fluorescence imaging. In particular, the use of multiple-pulse excitation enables the measurement of molecular fluorescence kinetics in a "pump-probe imaging" experiment. Thus we will be able to generate images where the contrast mechanism is the fluorophore relaxation time or lifetime, which is sensitive to the local environment (e.g., viscosity, pH, or ion concentration) of the fluorophore and thus is an even more powerful probe than simple fluorescence intensity imaging. The development of this novel and potentially revolutionary biological imaging tool will be a high priority in the next five-year period and will benefit from the interdisciplinary collaborations of Visiting Fellows (Brakenhoff) and Center participants in ultrafast optics (Norris), biological imaging (Axelrod), and fluorophore chemistry (Kopelman). The potential power of this new tool is greatly extended as a result of the recent development at CUOS of a 250-kHz OPA system providing us with sub-100-fs pulses in the entire 0.23–2.4-µm range, allowing direct single- or multiple-photon excitation of any fluorophore.

• Near-Field Scanning Optical Microscopy (NSOM). Our program for the coming five-year period will be to perform the first time-resolved experiments on transport and relaxation of electrons in low-dimensional semiconductor structures with high spatial resolution. The principal issues under investigation will be relaxation dynamics in quantum wires and single quantum dots, including effects of disorder; and ballistic transport in quantum wells and wires, including coherent excitonic wave-packet generation and propagation. This work is carried out in collaboration with a number of other research groups, including the Solid-State Electronics Lab at U-M, the STC for Quantized Electronic Structures (QUEST) at UC Santa Barbara, and Oxford University.

Ultrafast NSOM also will be applied to important problems in biophysics. In the Biomolecular Laser Spectroscopy Laboratory (Steel), there is presently under way an extensive program in the development and application of coherent laser spectroscopy using NSOM for the study of in vitro and in vivo protein structure and dynamics, and specifically the protein folding problem. CUOS (Norris) will couple to this effort through the use of short pulses to enable two-photon and three-photon excitation of specific amino acids located within the membrane-bound protein located near the tip of the near-field probe. The objective of the program is correlate various time-resolved luminescence signatures with stages of protein folding during and following protein translocation.

• Photoconductive Nanoprobe. In Sec. III.A.4 we discussed the development of a new photoconductive probe for launching and measuring high-speed electrical signals in ultrasmall electronic devices and circuits. The probe’s high sensitivity corresponds to the ability to detect less than one electron on a mesoscopic device, and opens the door to a whole new realm of high-speed semiconductor physics, namely the dynamics of mesoscopic transport. A large body of work has now been done in dc characterization of mesoscopic transport, such as ballistic transport in quantum point contacts and 1-D channels, tunneling, and Coulomb blockade. Our approach will be to use the nanoprobes to probe dynamics of electron wave packets through low-dimensional structures such as split-gate quantum wires, tunneling barriers, ballistic-electron tunneling and switching devices, and other mesoscopic structures. These measurements will allow us to directly observe for the first time the dispersion of wave packets in electron-transport devices and tunneling delay times of electrons through arbitrary barrier structures. This work involves collaborations between CUOS researchers in ultrafast optics, semiconductor physics, and terahertz technology (Norris, Nees, Whitaker) and outside collaborators (e.g., QUEST).

• Time-Resolved Studies Using Novel Short-Wavelength Sources. A major effort within CUOS is to develop and put to use new ultrafast light sources in the ultraviolet and x-ray regions of the spectrum. Because visible-wavelength light can only probe the outer electrons shared between the atoms in a molecule or in a solid, many scientific problems related to atomic motion and structure cannot be addressed using optical techniques. Ultrafast x-ray science promises to make it possible to directly observe dynamic atomic and molecular processes on both the time scale (femtosecond) and the spatial scale (nanometer) at which they occur.

The development of compact and reliable ultrahigh-peak-power lasers is the driving force behind progress toward this goal. Using various nonlinear optical techniques, high-power laser pulses can be converted into short-pulse uv light and x rays. Fundamental research in the physics of the x-ray generation process is discussed in the high-field section of this proposal. Many of the results from this work, especially sources in the ultraviolet and x-ray region of the spectrum, are already practical and the experimental techniques for using these and future sources are being developed. The nature of all of this work is very interdisciplinary and it will use many of the novel sources available at the Center. It will be carried out as a series of collaborations between Drs. Murnane, Umstadter, Kapteyn, Sension, Pronko and Penner-Hahn from U-M, and others, including Drs. Falcone(University of California - Berkeley), Downer (University of Texas - Austin) and Wilson (University of California - San Diego).

Recent work at CUOS has demonstrated the generation of ultraviolet light with unprecedented 10–20-fs duration, using harmonic generation in air [Backus 1996]. Pulses in this wavelength region provide the opportunity to study excited-electronic-state structure and dynamics in molecules with a detail that has been heretofore impossible. Initial experiments (1996–97) are being performed using pulses at 266-nm wavelength to study the ultrafast internal conversion processes in small polyene molecules (dienes and trienes). These studies are addressing open questions [Pullen, 1995] involving the ordering of electronic states in these simple systems, as well as the decay mechanism through the excited-state manifold to produce ground-electronic-state molecules. The state initially prepared decays in 10–50 fs with the ground state produced in less than 1 ps. Initial studies are being performed in solution. Future studies may also be performed in the vapor phase to explore the effect of solvation on the observed dynamics.

Future studies (1998–2000) will use ~ 10-fs excitation pulses in the 150–200 nm range. This wavelength range will be used to perform real-time studies of excited-state dynamics in a series of vapor-phase small molecules with inherently short-lived excited states. Examples of such species include ethylene, benzene, water, hydrogen sulfide and halogenated methanes. Impulsive excitation of these molecules will provide the opportunity to explore the excited-state structure and dynamics. For example, the lowest excited singlet state of water is a directly dissociative state producing H + OH. Using ultrashort pulses, one can also envision an experiment where the pulse is tailored to produce bond-selective dissociation on HOD molecules (HOD -> H + OD or HOD -> D + OH).

Soft x rays with sufficient flux for time-resolved photoemission can be generated using the high harmonic generation technique. Photoemission using uv and deep-uv light makes it possible to directly probe the excited-state dynamics of valence electrons in a wide variety of materials. This information is relevant to the design of microelectronics which operate at ever-faster speeds and with high internal electric fields. In past work, this technique has been used to observe late-time electron thermalization in metals and in direct- and indirect-band-gap semiconductors [Fann 1992]. At CUOS, we are constructing a uhv-capable experimental chamber for time-resolved photoemission. In initial experiments (1996–97), we plan to use sub-20-fs ultraviolet light to resolve for the first time the short-time thermalization of photoexcited electrons. A carefully done experiment should provide the most rigorous test to date of Fermi-liquid theory of electrons in metals, as well as being relevant to the dynamics of surface chemical reactions. Future experiments (1997–98) will include studies of electron dynamics in semiconductors in k-space regions where optical transitions are not allowed (i.e., indirect band gap) or where the data are ambiguous. We also plan to do detailed studies of electron transport in materials by illuminating a thin film from the back side as a pump and probing the electron energy distribution on the front surface.

Photoemission using soft x rays (1997–2000) can be used to monitor core-level electron energies. Since the energy of these levels depends on the local chemical environment of an atom, this technique is a powerful probe of the dynamics of the chemical state of materials. Furthermore, atomic structure also can be inferred from this information. High-resolution atomic-core-level spectroscopy using high harmonic x rays has already been demonstrated on a number of semiconductor, metallic, and molecular systems [Haight, 1994]. The extension of this work into the time domain represents an exciting and fertile area of research. In particular, processes involving surface reconstruction dynamics, surface desorption dynamics, x-ray studies of transient species, and phase transitions in solids and liquids are areas where significant new physics and chemistry can be investigated.

• Time-Resolved Electron Diffraction. As the above discussion makes clear, ultrafast short-wavelength pulses are anticipated to have tremendous potential for the investigation of structural dynamics of molecules and condensed systems. For the study of surface physics and chemistry, electron beams are particularly powerful probes. Ultrafast optical pulses may be used to generate short electron pulses, which have been used to time resolve structural phase transitions and lattice superheating [Herman 1993, Herman 1992]. We propose to use picosecond electron pulses to investigate surface dynamics by extending the technique of electron-stimulated desorption ion angular distribution (ESDIAD) into the picosecond time domain. ESDIAD is extensively used to determine the orientation of adsorbate bonds, adsorption site, and the vibrational properties of adsorbates. Time-resolved ESDIAD is expected to open many new possibilities for surface dynamical studies. Initial investigations following demonstration of the technique will include time-resolved vibrational relaxation (e.g., of Co on Pt(111)) and substrate/adsorbate photoinduced charge transfer.

• Time-Resolved Studies with Terahertz (Far-Infrared) Pulses. Research on terahertz-bandwidth pulses will keep pace with other ultrafast science and technology developments at CUOS. We plan to work to develop both the sources and applications in an interdisciplinary collaboration between groups in ultrafast technology (optoelectronics), ultrafast science (atomic and semiconductor physics) and high-field science (atomic and plasma interactions).

Right now good terahertz sources exist with up to 5 THz of useful continuous bandwidth, and peak power levels of about 1 MW at repetition rates of 10 Hz. Our goal for source development is 50 THz of continuous bandwidth, and power levels of 1 GW at repetition rates of 1 kHz. These improvements will be facilitated by the recent development of reliable amplified CPA sources of 20-fs pulses at 1 kHz, by Kapteyn and Murnane. Translating this bandwidth into terahertz radiation will not be achieved by a single breakthrough; work will proceed in the following areas. New media, such as plasmas or new nonlinear materials, offer the possibility of higher bandwidth coupled to high nonlinear susceptibility. We can also scale the nonlinear generators to large areas to take advantage of all of the energy in the CPA pulses. These development projects will be augmented by novel diagnostics, particularly those involving the unusual atomic processes discovered in the past four years, as well as some that have been predicted.

In atomic physics, one of the principal thrust areas will be in quantum control: bandwidth and power scaling of terahertz pulses can be used to implement new schemes for making and manipulating entangled wave packets in molecules for the purpose of controlling molecular dissociation, ionization, and isomerization. Robert Gordon of the University of Illinois at Chicago and Bucksbaum’s group have formed a collaboration to exploit this new capability. We will also make extensive use of the Fellows Program to begin applications work with scientists who can really make use of new sources of FIR. Included are possible collaborations with free-electron lasers (FELs) and with biology, chemistry, and plasma physics laboratories. (Plasma applications of terahertz pulses are discussed in Sec. III.B.4.)

Our ultrafast technology accomplishments have provided a foundation which will be used in the development of several exciting new areas. In particular, the expertise gained in ultrafast electrical pulse generation, propagation, and measurement will be used to produce novel diagnostic tools both for x-ray pulse measurements and for integrated-circuit characterization. New compact laser sources will also be employed in high-sensitivity photoconductive sampling systems.

• Ultrafast-Response Visible and xuv Detectors. The development of time-resolved x-ray techniques promises to open a new window into nature, making it possible to directly observe many fundamental microscopic processes. The potential of these techniques provides important motivation behind the technology development efforts at CUOS. During the past decade, the development of ultrafast x-ray sources based on laser-produced plasmas, high harmonic emission in gases, and synchrotron sources has advanced rapidly. The use of such sources makes it possible to resolve ultrafast processes using pump-probe techniques [Haight 1995, Workman 1996].

An alternate means of obtaining high time-resolution in the x-ray region of the spectrum is to use a time-resolved x-ray detector [Murnane 1990] together with a relatively long-duration x-ray pulse. This technique would make it possible to use synchrotron radiation sources for time-resolved extended x-ray absorption fine-structure (EXAFS) spectroscopy and x-ray diffraction studies. These detectors are also invaluable as a diagnostic for ultrafast x-ray sources and for high-field physics experiments, since the time history of the x-ray emission can greatly elucidate the physics of the interactions. For example, to understand the generation of coherent x rays from clusters or solids, it is necessary to distinguish prompt femtosecond-duration x-ray emission from delayed, thermal, picosecond-duration x-ray emission.

While the need for high temporal resolution grows rapidly, there is also a need for simple, low-cost diagnostics. A program that seeks to push the response of diagnostic tools to shorter time scales, by using to a great degree the previous accomplishments of the ultrafast technology area, will be pursued. It will also attempt in part to produce techniques that are simpler and less expensive than those currently in use. The instruments to be developed or enhanced include a jitter-free streak camera, a gated microchannel plate (MCP), and a photoconductive wave-form analyzer. The ultimate goal is for more than one of these instruments to be capable of picosecond resolution in an averaging mode within ~ 2 years, with 100-fs resolution or better within 5 years. Progress in the development of ultrafast subpicosecond x-ray detectors to date has been relatively slow. X-ray streak cameras with subpicosecond resolution (900 fs) have only recently been demonstrated [Chang 1996] in a collaboration between Zenghu Chang of the Xian Institute of Optics and Profs. Kapteyn and Murnane (now all at CUOS). Also, the new, low-jitter, optically triggered [Maksimchuk, 1996] streak cameras described in Sec. III.A.4 have been developed at CUOS.

These recent results, however, are preliminary. Our calculations show that by designing a new meander stripline sweep plate, coupled with a faster voltage ramp to drive the sweep plates, we can achieve higher sweep speeds, and thus faster time resolution. The devices will have to use the ongoing and future advances in a number of areas: fast, photoconductive (PC) switching of high voltages; ultrahigh-bandwidth electrical pulse propagation; and ultrafast optoelectronic measurement techniques. All of the proposed diagnostic tools will require extensive design, fabrication, and testing of high-bandwidth transmission lines. The concepts used to demonstrate the micromachined coplanar strips that supported subpicosecond electrical pulse propagation for > 0.5 cm will be applied and extended for the new devices in years 6–11. Designs for suspended microstrips are also under consideration for the high-speed streak camera, while new microstrips and coplanar striplines will be necessary for the gated MCPs and photoconductive detectors, respectively.

The ability to measure the electrical signals on the transmission lines as accurately as possible will also be of great importance if we wish to deconvolve the system response of the transducer from the measurements. This is currently accomplished through the use of a photoconductive sampling probe or a high-permittivity electro-optic crystal probe. The development of low-permittivity electro-optic polymers should contribute greatly to the ability to characterize electrical wave forms on streak plates or MCP electrodes. Photoconductive sampling will also be used in a compact, simple, all-solid-state photodetector/sampling gate system. This optical wave-form analyzer has been developed for use in the visible range, but we seek now to extend its usefulness to the x-ray regime.

Several experiments being planned will use the new, ultrafast x-ray detectors. X-ray emission from clusters and solids will be investigated. Also, in a collaboration with UC Berkeley, we are planning to use the streak camera at the Advanced Light Source synchrotron at Lawrence Berkeley National Laboratory, for an experiment to probe with hard x rays the laser-induced melting of a solid surface. Improvements in the x-ray PC wave-form analyzer and streak camera will also be relevant to visible or infrared detector and wave-form diagnostics. These wavelengths have applications in other areas of Center interest, including advanced medical ranging or imaging.

• Photoconductive Nanoprobe. There is currently a void in the area of microelectronics between the ability to produce complex integrated circuits and the ability to make measurements of components or regions within these circuits and diagnose faulty devices or other problems. We wish to enhance the usefulness of the fiber-based PC probe introduced in the achievements section so that it has the capability to measure either time or frequency domain signals for diagnostic troubleshooting within integrated circuits or multichip modules. Using the scanning force microscope to position the probe, which will be fitted with a sub-100-nm-diameter tip, first-ever measurements of the internal-node operation of large-scale integrated (LSI) circuits will be made. In addition, because low-temperature-grown GaAs is used as the active area of the photoconductive probe, we will also be able to demonstrate mixing of microwave signals with the harmonics of the laser repetition rate so that internal node measurements of millimeter-wave, or even submillimeter-wave frequencies can be made. A complete system will be integrated with a diode-pumped laser for compactness and ease of use. Use of diode-pumped compact sources will considerably enhance the sensitivity of this technique, as well.

Introduction. This section of the proposal discusses our research plans in high-field science and technology, at laser intensities far in excess of conventional nonlinear optics. As has often been the case in this field, new laser technology enables new science, and allows us to access new regimes of laser-matter interactions. There are several "grand challenges" in science and technology we seek to address through our research—visualizing and controlling wave-packet motion in a quantum-sized object using ultrafast laser and x-ray pulses, exploring radically new physics in the relativistic regime, devising new schemes for ultrafast x-ray generation, and controlling laser-matter interactions for micromachining and microsurgery.

Common to all the research efforts in high-field science is that we are working in previously uncharted regimes, whether micromachining or performing surgery with femtosecond pulses, or driving wakefields with broad-bandwidth pulses, or manipulating electron wave functions with rapid-rise-time pulses for coherent x-ray generation. Also common to all these areas is the integration and interdependence of the science and technology, the interdisciplinary nature of the projects, and the group effort required to make progress. This makes the research area particular well suited for a center-style approach. The novel laser technology on which this field depends is discussed in the optics section of the proposal. At the present time, due to the collection of expertise at the Center and the rapid advancement of our understanding of high-field effects and available optical technology, we have a unique opportunity to explore and exploit new regimes of science in the high-field area.

Exploration of the new field of high-intensity physics will be implemented in a collaboration among Phil Bucksbaum, Henry Kapteyn, Don Umstadter, Margaret Murnane, and Gérard Mourou. Research plans in these areas are discussed in Secs. I–III. There will also be significant involvement from others in this area, including Mike Downer (University of Texas - Austin), Ivan Christov (Sofia), Paul Berman (U-M), Robin Marjoribanks (University of Toronto), Robert Gordon (University of Illinois), and Eric Esarey (Naval Research Laboratory). Thus, we will have a critical mass of people to tackle the ambitious research we propose. Exciting applications of high-field effects that have impact far beyond high-field science are also planned. These include femtosecond laser micromachining and ablation, for precise control of optical damage, laser surgery, and materials processing. The group that is exploring these areas includes Ron Kurtz, Xinbing Liu, Peter Pronko, Gérard Mourou, and Henry Kapteyn. Research plans in these areas are discussed in Secs. IV and V.

One of the most exciting prospects made possible by the development of compact and reliable high-peak-power ultrafast lasers is the ability to generate short pulses in the ultraviolet and x-ray regions of the spectrum. People at CUOS have been among the leaders in the development of ultrafast x-ray techniques [Murnane 1991, Workman 1995, Zhou 1996, Chang 1996]. In the next few years at CUOS, we propose to use new techniques to increase the efficiency and wavelength range of coherent and incoherent x-ray sources, to the level where we can generate high fluxes useful for a wide variety of application experiments. High harmonic generation will be used to generate coherent xuv and soft-x-ray pulses of duration as short as 1 fs [Corkum 1993], and at wavelengths of interest to soft-x-ray microscopy and soft-x-ray projection lithography. Laser-produced plasmas will be used to generate large fluxes of incoherent soft and hard x rays. Finally, efficient x-ray laser schemes, at wavelengths as short as 15 Å, will be explored.

• High-Harmonic Coherent X-Ray Generation. Coherent ultrafast x-ray pulses can be produced simply by focusing a high-power laser pulse through a jet. Odd harmonics of the laser up to the 135th, with photon energy exceeding 200 eV, are produced [L’Huillier 1993, Lewenstein 1994, Kulander 1993]. These harmonics are produced as a result of the intense field ionization of the atoms. After being ionized, the electron released from the atom can be driven back to, and recaptured by, the parent ion when the laser field reverses. When this happens, the excess energy of the electron is released as a photon. In recent work using our very short 25-fs laser pulses, we observed harmonic photon energies up to 50% higher than previous experimental and theoretical results using longer 100-fs excitation pulses [Zhou 1996]. This result demonstrates that, even in laser fields strong enough make an atomic electron actually become unbound from the atom, ionization does not take place instantaneously. The efficiency of high harmonic production is also highest for shorter pulses, since the intensity required for ionization is approximately independent of pulse duration. We also demonstrated that the ultrashort-pulse-driven x-ray harmonics are continuously tunable, making them a very attractive source for experiments.

In our future work, we need to better understand the interaction of 10–20-fs light pulses with atoms. In this work, we are approaching a new nonadiabatic regime in laser-atom interactions [Christov 1996], where the ionization rate for an atom is no longer simply a function of the intensity of the light, but is also affected by the short time duration of the pulse. By decreasing the laser pulse width from its present 25 fs to 10 fs, we expect to be able to observe new physics of the interaction of light with matter. From the point of view of x-ray sources, using 10-fs pulses will allow us to improve the conversion efficiency of the x-ray generation by 1–2 orders of magnitude compared with the 100-fs case, and to generate photons in the "water window" (> 270 eV). Also, since the harmonics are generated only on the leading edge of the excitation pulse, the x-ray pulse will be at most a few femtoseconds, possibly subfemtoseconds, in duration. New methods to measure the duration of the harmonic pulse will have to be devised. All of this work (including the application experiments described in other sections of this proposal) will be enabled by our development of a state-of-the-art 10-fs, kHz, high-average-power laser to generate an x-ray beamline, with usable x-ray flux within two orders of magnitude of that available from synchrotrons. The great importance of using very short pulses is that they allow us to reach very high laser intensities with relatively modest energy.

• Cluster and Solid Sources. We also plan to investigate coherent and incoherent x-ray emission from high-pressure gas jets, clusters and solids [Gibbon 1996, Ditmire 1995]. Because of the ultrashort excitation pulse, we expect that the clusters will survive structurally during excitation. (For longer laser pulses, clusters explode during the leading edge of the pulse.) In fact, precise control of the explosion of the cluster will allow us to optimize the x-ray emission. This should allow us to generate higher brightness x rays, with significantly shorter wavelengths. Shorter wavelength coherent x rays might also be generated using solid targets, according to recent predictions.

• X-Ray Lasers and Plasma Sources. Ultrafast x-ray pulses can also be generated from laser-produced plasmas, which we demonstrated in past work [Murnane 1991, Workman 1995, Zhou 1996]. This source produces a bright and continuously tunable x-ray spectrum. Laser-plasma x rays have relatively long pulse duration (0.3–5 ps) in the vuv and x-ray region, but extend to shorter wavelengths than with high harmonics, where their pulse duration should also be subpicosecond. We have preliminary evidence that, using shorter laser pulses, we can generate higher temperature plasmas and, as a result, shorter wavelength and higher brightness sources. These incoherent x rays can also be used as a "flash lamp" excitation source for photoionization-excited x-ray laser schemes, with a laser wavelength as short as 1.5 nm [Kapteyn 1992, Apruzese 1996]. The pulse energy requirements for these schemes scale very strongly with pulse duration. At present, we are developing at CUOS a 0.5–1-J, 10-fs laser, which is sufficient to test this laser scheme. This laser requires novel approaches to short-pulse amplification, and is discussed in the optics section of this proposal.

• Propagation in Overdense Plasmas. A consequence of the change of electron mass is a change in the electron plasma frequency. When the plasma frequency exceeds the laser frequency, or the density exceeds the critical density, a light wave is evanescent and decays exponentially on the scale length of a skin depth. If the plasma frequency changes due to the mass shift, then a material that is opaque to a low-power laser of given frequency will become transparent to the same laser light at higher power [Lefebvre 1995].

• Gigagauss Magnetic Fields. Gigagauss magnetic fields, the highest ever in laboratory experiments, can be created by the large current densities that result from the interaction of a high-power laser with a plasma. Several different physical mechanisms have been discussed [Bychenkov 1993]. We plan to investigate these fields in collaboration with Dr. Rupasov, a group leader at the Plasma Diagnostics Laboratory at P. N. Lebedev Physics Institute of the Russian Academy of Sciences. His group has developed and used at different experimental facilities a three-channel polarointerferometer, which is able to provide simultaneous measurements of the changes of the polarization angle and the phase shift of the probe laser beam. That makes it possible to reconstruct the magnetic induction, averaged over the optical path length with high spatial and temporal resolution [Pisarczyk 1990, Kas'yanov 1994, Kas'yanov 1993].

• Self-Channeling of High-Intensity Pulses. Self-channeling of high-intensity pulses is important for a number of applications, and we need to develop a better understanding of the phenomenon. For instance, in the case of self-guiding from the interplay between nonlinear self-focusing and plasma defocusing [Liu 1993A, Braun 1995], it is unclear how much the light background contributes to the propagation. Preliminary investigations indicate that it is playing the role of a photon reservoir by feeding energy to the channeled pulse and helping balance the loss of channeled energy by multiphoton ionization. We are planning to investigate the nonlinear propagation for extremely short pulses down to 10 fs with different gases as a function of gas pressure. Ultimately, we hope to use this plasma channel to guide a much higher intensity_ laser pulse.

• Wakefield Acceleration. Finally, the concept of wakefield acceleration of ultrashort electron pulses through laser injection with multiple laser pulses [Umstadter 1994, Umstadter 1995, Umstadter 1996A] was discussed in the research highlight section. We will use this scheme to generate femtosecond electron pulses. Among other applications, we will explore the possibility of using them directly to do ultrafast studies, such as pulsed radiology, or to generate coherent undulator radiation in the x-ray region. Through separate funding (because of the very large-scale nature of the project), we hope to eventually accelerate these million-electron-volt-energy electrons to giga-electron-volt energies.

Our five-year research program will be directed toward understanding the fundamental strong-field quantum many-body interaction. Elements include high harmonic generation (discussed in the Sec. I); strong-field molecular dissociation and unimolecular chemistry; strong-field multiple excitation; laser-dressed relaxation processes, including interactions of atoms with relativistic continua; half-cycle pulses; and coherent control of atomic and molecular systems.

• Molecular Dissociation. Early experiments on the dissociation of molecules in strong laser fields showed a strong tendency for the molecules to align and distort in the presence of fields exceeding about 0.5 V/Å [Yang 1991, Zavriyev 1990, Normand 1992, Dietrich 1993]. More recent work at NRC and Saclay has revealed the even more remarkable tendency of higher-Z molecules to multiply ionize once the distortion reaches a critical interatomic separation [Schmidt 1994, Stapelfeldt 1995, Seideman 1995]. The ionization is followed by a "Coulomb explosion," as atomic fragments are blown apart by their own charge, once the binding electrons are gone [Cornaggia 1995]. The Coulomb explosion phenomenon is more than a basic science problem; it may have some very useful applications in the production of ultrafast electron and ion sources. Since ionization happens at a critical point in the motion of a laser-driven molecule, shaped optical pulses can be used to tailor the electron burst in a number of ways, including the creation of multiple coherent bursts of electrons, or controlled electron pulse durations. Coulomb explosions occur in polyatomic molecules as well, providing another avenue to control unimolecular chemistry. We would like to study, and ultimately control, the fragmentation patterns from compact polyatomic molecules such as substituted methane-like compounds, and form long chains, as well. The distortion induced by a strong laser field is a possible way to dissociate non-thermodynamically favored products.

• Atomic Multiple Excitation. The phenomenon of above-threshold ionization (ATI) has some strong elements of multiphoton physics, such as the appearance of intermediate-state resonances [Freeman 87]. It also has some strong elements of classical scattering physics, such as the general shape of the electron spectrum and its dependence on intensity and laser wavelength [Corkum 1993, Schafer 1993]. Both classical and quantum models show that only the lower energy ATI peaks are mainly due to the motion of a single active electron. By studying the high-energy peaks, we can get a clear picture of multiple electronic excitation at this boundary between quantum and classical physics [Lewenstein 1995]. This is a new frontier area for study. Within this region of ATI spectra above the classically allowed ionization energy, there are broad new spectral features, which are evidence for multiple excitation [Van Woerkom 1996, Bucksbaum 1996]. We plan to study these phenomena further, to elucidate the mechanisms for multiple excitation with strong fields.

Recent experiments in Berkeley and Saclay have shown that multiple excitation can be used to cross-correlate vuv laser pulses [Schins 1996, Glover 1996]. These experiments rely on the notion that basic relaxation processes, such as Auger decay, are not much altered by strong laser fields. At some level, however, this must break down, as multiple pathways for relaxation involving one or more laser photons become available. If laser-dressed electron spectroscopy is ever to become a tool for characterizing vuv photons, then the process must be understood in its entirety. We propose to study multiple excitation in experiments involving vuv harmonics combined with intense laser pulses, in atoms and molecules.

• Half-Cycle Pulses. In the next five years, several important applications for broadband, coherent "half-cycle" pulses will be investigated at CUOS. These pulses propagate and reflect from metallic mirrors like light pulses, but they have some unique properties. For example, half-cycle pulses can exchange energy with free electrons, since the time-integrated electric field is non-zero. The pulses can also be shaped to provide light sources with properties not obtainable with other far-infrared devices. We plan to analyze terahertz propagation from relativistic wakefields, using techniques learned from our production and detection of these pulses in the laboratory [Jones 1995A, You 1994, You 1993]. In addition, it is possible that such wakefields may be an important source of such radiation.

Half-cycle pulses might be efficiently upconverted by reflection from a relativistically driven plasma density gradient [Kapteyn 1991]. Such upconverted pulses would have some significant advantages over other mechanisms for producing short pulses. For example, they would have central wavelengths controllable from the infrared to the ultraviolet. In addition, it is relatively easy to scale up the energy in these pulses, compared to harmonic generation.

• Coherent Control of Atomic and Molecular Dynamics. One of the most important applications of half cycle pulses is the control and analysis of wave packets in molecules. A new method for bond-selective photochemistry uses shaped, strong, ultrafast optical pulses to engineer special electronic and nuclear nonstationary states. Control is possible when these states are produced faster than the time scale of the internal motion. A research program to investigate this has begun in Bucksbaum’s laboratory on Central Campus. We expect CUOS to participate in this program through collaborations and visitors. In one manifestation of this central idea, ultrafast optical pulses put energy into electronic wave packets of Rydberg states, which form when a laser pulse excites a Rydberg system faster than the period of the corresponding Keplerian classical orbit. The energy shelved in Rydberg wave packets can be transferred back to the ion core as the wave packet moves or changes shape.

Development of femtosecond micromachining applications will be pursued in collaboration with commercial companies. We feel that femtosecond micromachining is well-suited for applications where high-precision, micron- and submicron-sized holes and lines are required. Specific targets include hole drilling and submicron dry etching for the next generation of integrated circuits for microelectronics, laser source for three-dimensional optical data storage devices, and automotive applications such as fuel injector nozzle holes. Harmonics of the fundamental laser frequency will be used in combination with ultrashort pulse duration to further improve the micromachining quality. We will continue to push the smallest feature size down to the 0.1-µm range.

The basic physics associated with the laser micromachining process—laser-induced breakdown, energy deposition, ablation mechanism and rate, shock-wave propagation, and heat transport—will also be studied in order to better understand the machining process and optimize laser parameters. It is also important to extend our damage threshold study to pulses in the few-optical-cycles regime. In this regime, tunneling may prevail over impact ionization and multiphoton absorption. Propagation effects of femtosecond laser pulses relevant to micromachining will also be studied.

In parallel with the basic science, major engineering efforts must be undertaken in order to achieve our application goals. For example, beam delivery systems and work stations with multi-axis motion and beam scanning capabilities must be developed. In conjunction with the medical laser program, compact, rugged, reliable, high-average-power ultrafast laser systems suitable for industrial use will be developed. There are many applications of laser ablation in the medical, bioengineering, and engineering areas. Because of the sub-Rayleigh volume resolution there is a distinct possibility to be able to operate within a single cell. We also want to investigate the potential of this technology for 3-D data storage and for dry etching, both for flat-panel and integrated-circuit applications. This technique also has applications to thin-film deposition in vacuum and gaseous background environments and to the creation of novel materials in thin-film form using ultrafast laser ablation as a source for film deposition. Our future work will establish computer models for ultrafast energy absorption and dynamical breakdown of materials under high-intensity laser irradiation.

In other related work, the application of high-peak-power lasers to the formation and control of million-electron-volt ions appears to be a viable method for generating beams of high-energy ionic charged particles. Investigation of this phenomenon could lead to important breakthroughs in ion beam technology and its application in basic science, engineering, and medicine. High-energy ions are observed to form in ultrafast laser ablation plumes exhibiting high charge states and energies approaching the million-electron-volt range. It is speculated that these energies are imparted to the ions by an acceleration process associated with plasma double layers. These develop within an ablation plume from charge separation effects associated with suprathermal hot electrons that are hydrodynamically removed from and carried ahead of the leading edge of the ablation plasma. Ions in the plasma are then accelerated toward these negative electron charge distributions. Experiments are currently being set up to analyze these ions in terms of their distribution in charge state and energy. Such information will help in determining details about the acceleration process and in understanding the mechanisms involved.

Responding to industrial needs for faster and more accurate measurement of three-dimensional objects such as automotive parts, the Center has come up with a scheme to use femtosecond laser pulses for optical metrology. With the help of U-M’s TMO, practical applicability and marketability are being evaluated.

Future work in this area will include the following:

In the six years of its existence, the Center has provided unparalleled opportunities and resources for the training of graduate students in the ultrafast optical sciences. The Center has provided support for over 50 graduate students through its research assistantship program. In addition, 12 incoming graduate students have been awarded prestigious STC Fellowships. Half of the fellowship recipients have been women or members of underrepresented minority groups. A number of other graduate students are involved in research at the Center but are supported by other sources.

The Center has also been successful in attracting other major fellowship programs for the support of graduate students. Three years ago we were awarded five NSF graduate traineeships, each of which will fully support a student for five years. Last year a proposal written by the Center’s associate director for education won seven fellowships in the Graduate Assistance in Areas of National Need (GAANN) program of the U.S. Department of Education. While these fellowships are intended for the entire electrical engineering department, several of the present incumbents are conducting research at CUOS. A novel feature of the GAANN program is that the fellowship holders are trained in both teaching and research in order to prepare them better for academic positions.

The Center provides an intensely stimulating intellectual environment for its graduate students. Each graduate student affiliated with the Center is asked to make a presentation on his or her research to an audience of faculty and students. Most graduate students have also been coauthors on journal articles that report Center research. Of the 300 journal articles and conference papers published by Center researchers, 90% have had graduate student co-authors.

A graduate seminar on ultrafast optics brings to campus each week one of the leaders in the field. Among recent seminar speakers have been Profs. Hermann Haus and Erich Ippen (MIT), Drs. Dan Grischkowsky (IBM) and Anatoly Grudinin (Southampton University), and Dr. Phil Sprangle (Naval Research Laboratory). In addition, last year we introduced a new 3-credit-hour lecture course Ultrafast Optics (EECS 546) that covers the theory and experimental techniques behind ultrashort pulse generation, amplification, propagation and manipulation. With this course we are able to link graduate instruction to the current research that goes on at the Center. Last year we also inaugurated a practice-oriented Masters of Engineering degree program in Ultrafast Optics. In this program the student works on an industrially relevant thesis project with one of our industrial partners after completing a set of core optics courses.

We have increased interactions with Minority Research Centers of Excellence (MRCE) through a Visiting Graduate Student Program. Several graduate students from Hampton University have spent part of the summer conducting research in our laboratories.

Graduate students are encouraged to participate in our many educational outreach programs. They serve as instructors and assistants in programs such as Future Science: Future Engineering for middle-school girls and do tutoring of secondary students. Those who are most active in our outreach effort are rewarded with free trips to technical conferences.

At the undergraduate level, the CUOS has focused its efforts on providing meaningful research experiences for students who show some potential for graduate study in science and engineering. In the five years since CUOS was established, more than 30 undergraduates have been supported with NSF funds to conduct research at the Center. Another 20 students have worked with the Center faculty with support provided by other programs.

Students are recruited nationwide, with particular attention given to those from smaller undergraduate institutions that do not provide the range of research experiences available at a research university like the University of Michigan (U-M). The targeted institutions include most of the women’s colleges and the historically black colleges and universities. We annually send information and application materials to over 300 such institutions. In addition, numerous students have located our Web site and have submitted applications based on information found there. Each year we receive about 30 applications for the six summer positions. Students are selected on the basis of grades and letters of recommendation.

During the first two weeks of this ten-week program, the undergraduates assist with "Future Science: Future Engineering" (formerly SummerScience for Girls), an outreach program for middle school girls between the 7th and 9th grades. By teaching the principles of physics to younger students, the undergraduates gain a firmer grasp of the subject. While working with these girls, the students are simultaneously working with Center faculty on the research projects that will occupy them for the balance of the ten weeks. They also attend research seminars, as well as workshops designed to help them with graduate school preparation and career choices. In addition, there is an ethics component that uses guest lecturers, assigned readings, and role-playing activities to teach, among other things, the societal responsibilities of scientists.

There are ample opportunities for social interactions and cultural activities, including picnics, canoe trips, excursions to the Shakespeare festival in Stratford, Ontario, and outings to Ann Arbor’s summer art fair. The students generally live in group housing and develop a sense of community during their stay here.

At the end of the program, the students present their research results orally at an on-campus conference attended by students and faculty and turn in a written report. Some students have been co-authors on papers published in scientific journals or presented at major conferences.

• Background. As an NSF Science and Technology Center, CUOS is mandated to work to broaden the pool of future scientists and engineers to include a more diverse cross section of the American population. K–12 outreach is a natural part of this effort, since it is simply too little and too late to try to recruit underrepresented minorities at the graduate or undergraduate level. A long-range perspective requires that we improve science and math education at all grade levels, while exposing children and teens to career exploration activities that can motivate them to pursue the educational foundation necessary for technical careers.

• Stakeholders for Systemic Change. Over the past four years, CUOS has learned that the only way to make fundamental and systemic change in education is to involve everyone with a stake in it: students and parents, teachers and administrators, business and community organizations, and colleges and universities. We realize that assisting youngsters with their learning is a labor-intensive endeavor and requires a long-term commitment to building relationships among all of those involved. An occasional tour and career presentation or a few science demonstrations rarely will make a lasting difference in the lives of children. Given the fact that CUOS faculty and students are engaged full-time in research, K–12 outreach efforts cannot take up a great deal of their time and lives. The only way any of us can have a significant impact is by linking the efforts of many people and organizations. Accordingly, CUOS’ K–12 Outreach Office helped form, in the fall of 1995, the Southeastern Michigan Math-Science Learning Coalition, involving partners from K–12 education, parent groups, government, higher education, business, and community groups such as museums, youth centers, 4-H Extension, and other nonprofit educational groups. Our vision is to link and connect people and resources with educators, children, and parents so that all youngsters may receive help learning math and science and may enjoy a wide variety of experiences to explore career interests.

Through coalition-building efforts, CUOS has found that many groups have been doing similar projects for children to promote math and science and career awareness with a partner or two, with limited staff and volunteers, and in isolation from one another. The coalition provides a mechanism to bring together stakeholders who, by working together, can reduce duplication of effort and extend the reach of all groups and resources. To date, some 65 previously disparate individuals and groups have come together to build a critical mass, resulting in an explosion of creativity and cooperation. Within the University of Michigan, and just through word of mouth, 28 departments, museums, and centers have stepped forward to join efforts. The medium for this organization, as clichéd as it might sound, has been cyberspace. As a university-based organization, CUOS is able to develop and offer to others a World Wide Web site to manage and communicate partners’ resources (located at http://www.eecs.umich.edu/mathscience). As of June, 1996, there were several hundred resource "pages" on this Web site.

Through the K–12 Outreach Office, CUOS manages the Coalition Web site, facilitates matchmaking among resource partners with schools and community centers, provides a K–12 Outreach Office to enable university students to pool and maximize their community service activities, and manages a K–12 Laboratory where partners provide science experiments for children on campus. In addition, CUOS continues science programs and laser laboratory tours for children through partnerships established during the early days of the Center. These include the Center for the Education of Women’s "Future Science: Future Engineering" program (formerly SummerScience for Girls), optics classes on spring Saturdays for the Detroit Area PreCollege Engineering Program (DAPCEP), and science workshops at Pontiac Owen Elementary and Detroit Lessenger Middle Schools. Our commitment is to promote learning communities and stakeholder development in Southeastern Michigan, Detroit, and Pontiac so that, working together, we can strive to reach mutual goals whereby all youngsters become math and science literate and gain awareness of the vast array of careers they might pursue after high school.

• Introduction and Overview. The Center has participated in active industrial collaboration ever since its creation in 1991. These activities established the groundwork for a more formal definition of industrial liaison policy and for the present Industrial Associates program, which was implemented over the past four years. Technology transfer activities have included assisting in the formation and stabilization of new companies, establishing contractual programs with industrial partners, initiating and managing new patent applications, and continuing cooperation with current and new corporate and industrial partners.

Industry is invited to participate in developing state-of-the-art ultrafast lasers and applications of new ultrafast-pulse technology. This activity may be integrated with the Master of Engineering degree (MEng) program, which was recently established for the Center through U-M’s Electrical Engineering and Computer Science Department. A central component of this degree program is a practice-oriented thesis project that is intended to involve industry participation through a collaborative research effort on new product development or other industrial problem-solving activity.

The Center has established a program whereby industrial associates may participate in on-site laboratory activities through the Center’s Ultrafast Development Laboratory (UDL), which makes laboratory space available for specific periods of time, so that they can explore solutions to problems or test new products.

When work that is performed under the UDL program is of proprietary interest to individual associate members, appropriate contractual agreements are made to safeguard these interests. UDL operates with the full intellectual support of the Center’s faculty and staff. In many cases, joint publications of scholarly work result from the interaction.

It is explicitly understood that the corporate associates will move developing ultrafast technology into their commercial product and process lines. The university’s interest, if any, is represented through published works and agreements that are executed through its Technology Management Office and/or its Division of Research and Development Administration.

Industrial participation in the UDL is predicated on a balanced contribution of financial and in-kind support. This typically consists of a combination of cash, professional labor time in collaborative research or student mentoring, and equipment loans or donations. University sub-contracting in Small Business Innovation Research (SBIR) and Small Business Technology Transfer Research (STTR) projects is also encouraged.

• Specific Activities. Specific programs and relationships are reviewed on a yearly basis; multiyear programs are not unusual. Working relationships may range from simple collaborations to contractually binding agreements.

• Examples of Companies and Associated Areas of Interest. Picometrix: picosecond photodetectors and sampling gates; Ford: picosecond lasers for automotive sensing applications; Meridian Instruments: femtosecond pulses applied to confocal microscopy; Nanocrystals: optical properties of quantum dots for flat-panel display; IMRA America: fiber-based femtosecond laser oscillators; Clark/MXR: high-peak-power femtosecond lasers for research; Medox Electro-Optics: fast optoelectronic switches and streak cameras; Meadowlark Optics: technology for shaping ultrafast pulses; Newport Klinger: precision positioning technology; Coherent Laser Group: applications of high-power pump lasers; Owens-Corning: femtosecond laser micromachining in steel; 3M Corp.: program on micromachining with picosecond pulses; IBM: micromachining in semiconductors; Kaiser Optical Systems: holographic gratings; Kapteyn/Murnane Labs.: Sub-100-fs lasers.

• Spin-Off Companies. The formation and stabilization of spin-off companies is a high priority for the Center. The status of several such companies is documented below:

Picometrix was founded by Steve Williamson (a former member of the research staff at the Center) in 1992 to develop the use of ultrafast photodetectors for research and for other direct commercial applications. Picometrix started its business life as a full-time resident of the Ultrafast Development Laboratory at the Center and here developed their first of an ongoing line of photodetector products. Picometrix now has 7 full-time employees, 4 products in the marketplace, several new products under development, and a collection of SBIR projects under way. A continuing interaction occurs between scientists and engineers at Picometrix and at the Center, especially in the area of fast-semiconductor-response physics and its applications.

Phillip Bado, a research scientist from the Center, founded MXR Research in 1992, which later merged with Clark Laser Systems of Rochester, New York, to become Clark/MXR. The company is currently located some 12 miles west of Ann Arbor. Their product line consists of a selection of ultrafast lasers that are recognized as setting the standard in the industry. These include discrete component and fiber-based systems. At this time they have 15 full-time employees, 3 major laser system products, and an array of control and diagnostic products for ultrafast lasers and optical devices. Clark/MXR is very active in SBIR research and collaborates heavily with the Center and other universities in developing its product lines.

Colleagues who are now associated with the Center founded Medox Electro-Optics in Rochester and moved it to Ann Arbor, in order to maintain a close liaison with the Center Medox, which manufactures fast optical switches for use in laser systems, currently has 5 full-time employees, 2 products in the marketplace, and is developing, under an aggressive research program, advanced designs for ultrafast streak cameras to be used in research and commercial products. Its president, Marcel Bouvier, maintains a close working relationship with the Center and participates in the UDL program on an as-needed basis.

• Patents. The Center has had a continuous flow of patents that are applied for through U-M’s Technology Management Office (TMO). For the period up to mid-1996, there have been 31 invention disclosures made to TMO, 12 patents applied for (but not yet granted), and 6 patents granted [see Appendix E]. From this group, 3 licenses have been sold and 4 more are under negotiation. In addition, there are two patents that are associated with specific U-M business development activities that involve potential venture capital and joint venture projects.

• Business Development Activities. A new spin-off business, involving the application of femtosecond lasers in ophthalmology, is in the planning stage. Research has been under way, in collaboration with U-M’s Kellogg Eye Center (KEC), to capitalize on the considerable benefits associated with ultrafast laser pulses in precise opthalmological surgery. Ron Kurtz, MD, heads a group of scientists from KEC and CUOS who have been exploring possible treatments of glaucoma and cataracts, and procedures for retinal surgery. Discussions are proceeding with commercial firms to establish business liaisons and strategic plans for launching a spin-off business to make use of the techniques being developed, as well as the compact lasers being designed and built as part of the program. TMO has completed a commercial analysis of this project and we anticipate that specific business deployment action will occur in about one year.

The Visiting Fellows program was initiated in 1993 to encourage national utilization of CUOS facilities by scientists and engineers. In this way, we can broaden the scope of science activities in CUOS and foster wider interdisciplinary collaborations. Visitors are a major component of the Center, using 14% of our NSF funds this year. The program consists of several components: Sabbatical Fellows, Center Fellows, Visiting Scholars, workshops, and a speakers program.

Sabbatical visitors are typically on one-year research leave from their home universities. They are given visiting professor status in physics, chemistry, or engineering, and they have offices and share laboratory space in the Center. Sabbatical Fellows from 1993–96 were C. Conover, Colby College; M. Downer, University of Texas; R. Gordon, University of Illinois, Chicago; P. Klein, Naval Research Laboratory; R. Marjoribanks, University of Toronto; A. Migus, ENSTA/CNRS; and S. Ruhman, Hebrew University.

The position of Center Fellow is patterned after the Michigan Society of Fellows. These are typically appointments of 1–3 years to young independent scientists. We have already had more than a dozen Center Fellows in physics, electrical engineering, and ophthalmology (a shared appointment with U-M’s Kellogg Eye Center). Several have gone on to faculty positions or jobs at national laboratories or in industry.

Visiting Scholars are scientists who come to collaborate with other scientists in the Center. This flexible program accommodates single investigators, small groups, or students who would like to use our facilities or learn about our techniques. In several cases we have accepted students working on advanced degrees at other institutions but carrying out independent work at CUOS. More than 50 scientists per year take advantage of this program.

The Fellows Program is also able to work together with other programs to facilitate participation from outstanding scientists worldwide. For example, we have recently invited a Humboldt Fellow to come from Germany to be a CUOS Fellow. We have also benefited from long-term visits from CNRS in France, from the Naval Research Laboratory, from FOM Institute in Amsterdam, from Los Alamos and Livermore National Laboratories, from the Max Born Institute in Berlin, and from universities and colleges in Europe, South America, Canada, Israel, and the US.

Five workshops have been held to date, which bring 10–20 scientists to Ann Arbor for 3–5 days of intense work on a single topic. The Visiting Speakers program invites speakers in physics, chemistry, optics, and electrical engineering to spend 2–3 days at CUOS, highlighted by a talk at the Center or in one of the associated departmental colloquia. This is intended to increase contact between the Center and the International Community, and to enrich the scientific environment for students and staff.

The program has supported approximately 130 visitors and fellows since its inception, approximately 35% workshop participants, 30% visitors, 20% speakers, and 15% fellows.

With the recent award of an REU site grant we have been able to expand our undergraduate research program. In the next several years we plan to increase the numbers of undergraduates who conduct research at the Center throughout the academic year. These students will be recruited from the University of Michigan and universities such as Eastern Michigan, Wayne State and Oakland University that are within commuting distance. We believe that an extended research involvement throughout the academic year will enhance the students’ commitment to research and also yield more significant scientific results. The undergraduate curriculum is also being enriched by the addition of a new laboratory course in optics developed by members of CUOS.

CUOS K–12 Mission and Goals. The CUOS mission for K–12 and Community Outreach is to "Support community coalitions in order to provide science and mathematics educational opportunities for all children." Goals are to (1) promote systemic educational reform by helping communities build coalitions to leverage and link science and mathematics educational resources and career information to all children; (2) ensure all children have access to hands-on and discovery-based learning experiences promoting scientific and mathematical literacy; and (3) provide all children opportunities to explore careers within science, mathematics, technology, and engineering fields.

• Goal 1: Programs and Activities for Coalition Building. CUOS is providing leadership to firmly establish a coalition to connect and coordinate U-M and Southeastern Michigan math and science resources with teachers, parents, and others who provide children with learning and career exploration experiences. The CUOS K–12 and Student Outreach Office designed and maintains a World Wide Web resource directory for the coalition. This Web site is the door to (1) a growing body of hands-on science lessons and experiments that people can try at home or in schools and science clubs; (2) a directory of "Wandering Wizards" who will bring experiments requiring more expertise or more elaborate equipment to schools and youth centers; (3) listings of people willing to do career presentations or to allow job shadowing; (4) exciting tours of laboratories, museums, and work sites that are available to groups or individuals; (5) information on training available for tutors at schools, community centers, and CUOS; (6) classes, camps, and training opportunities for parents, teachers, and children, and (7) a great deal of information on how people in other areas can form such coalitions themselves. The Web site is a vehicle to communicate CUOS, university, and others’ resources to the broader community; even many U-M personnel and students have been surprised to learn how much the university has to offer.

We believe the coalition and Web resource system is a model other STCs, schools, companies, and community groups can modify and replicate to leverage, communicate, and promote the sharing of resources in their own communities. Our current focus is on recruiting partners within the University of Michigan, parents of children at sites where we provide services, and community-based organizations. Later, we will target the involvement of companies and other higher education groups, including STCs. An example of expanding stakeholders across the country is our current work with University of Oklahoma’s STC for the Analysis and Prediction of Storms education coordinator to polish their weather lessons and place them on our Web site. Eventually, the coalition-building process and the Web will enable many groups to communicate and share their exciting and effective science resources and career information with people in their own delivery area, as well as with the rest of the country.

NSF awarded CUOS a three-year supplemental grant in February, 1996, to provide the seed funding necessary to enable Pontiac Owen Elementary and Detroit Lessenger Middle Schools to build their own learning community coalitions. Working together and sharing models and strategies, we are reaching out to parents and local business and community members to broaden learning and career exploration opportunities for children during and after school, on evenings and weekends, and during summers. These two communities also utilize resources being cultivated from the university and the Southeastern Michigan Math-Science Learning Coalition. Perhaps the African proverb, "It takes an entire village to raise a child," best describes the motivation and work being done to forge coalitions, to heighten stakeholder development, to solidify commitments to children and their learning, and to rebuild circles of support among community members for children.

• Goal 2: Strategies for Hands-On and Discovery-Based Learning. [Note: Underlined print below denotes hyperlinks on our Web site.] CUOS and coalition stakeholders realize that children need far more hands-on, fun, discovery-based learning experiences related to math and science. CUOS has designed a component on the Web resource clearinghouse to organize and communicate easy-to-do lessons for children across science areas. This directory provides plenty of ideas for fun projects for educators, club leaders, parents, and even tutors.

Some lessons require special equipment and knowledge and therefore need to be offered by those with expertise and with access to materials. For the past four years, CUOS has had such "Wandering Wizards"—faculty and students who share laser and other favorite science demonstrations with children in Detroit Lessenger and Pontiac Owen Schools, the Center for the Education of Women’s summer science program for girls, DAPCEP, and the Ann Arbor African-American Academy Saturday program. We now recruit many people willing to share the same experiments and we post these opportunities on the Web site so more children can enjoy them. Another important aspect of the Wizard program is the continuity it provides. CUOS and others have often had special people who went out to share experiments, but when these students graduated or faculty left, their lessons disappeared with them. Now, we are able to capture the "recipe" for favorite experiments and to recruit others to continue to offer them to youngsters.

CUOS encourages teachers, parents, and coalition partners to work together to form science and career clubs, either as part of the classroom or as an after-school enrichment program. We realize that many youngsters have a significant amount of time after school every day that is unstructured, unproductive, and unsupervised. Children need groups to belong to, activities to be part of, far more adults to know, and more support in general to keep learning outside of school. Working with 4-H Extension, teachers, and parent groups, many schools, churches, and community centers are expanding or starting a wide range of after-school programs. Several teachers are incorporating clubs and experiential learning activities within their curriculum. Our main thrust is to bring more adults into the lives of children to engage them in far more hands-on science learning experiences and to assist their establishing career goals and realistic road maps to achieve these goals. Lessons, Wizards, and career opportunities on the Web site are all beneficial resources for parents, teachers, and others who are engaged in these kinds of clubs.

From interactions with children, it has become clear that many need individualized tutoring to help them acquire skills, successfully complete homework assignments, and generally gain confidence to take more math and science classes. In Washtenaw County, CUOS serves as a central hub to recruit, train, and match faculty and student math and science tutors from U-M with area schools, public housing centers, and community youth centers. During the 1995–96 school year, 55 tutors served 91 children and teens in ten sites. Each tutor made a minimum once-a-week commitment for at least a semester. Some tutors worked with one child, others assisted a small group of youngsters during classroom instruction, and a few managed after-school study groups. Gérard Mourou, CUOS director, believes so much in this individualized support for children that he approved up to four hours a week paid release time for CUOS faculty and students to tutor. Mourou "walked the talk" by tutoring in a community Saturday program as well as at CUOS. When some CUOS scientists and university students shared that they did not have the time to travel to and from a community or school site, Mourou started an afternoon tutorial at CUOS. Two area high school principals and a few teachers helped us get the word out to students about this opportunity. By the end of June, 22 teens had made arrangements to come to the campus site weekly for tutoring. Feedback across children and tutors clearly indicates that this serious commitment of time is well spent. Youngsters share a sincere appreciation for the individualized support and note improvements in both grades and confidence. Perhaps more importantly, the feedback sheds light on the value children and tutors both place on their relationships and on the less formal learning and support that results from the sharing of ideas and experiences.

At one time, CUOS considered having students and faculty travel to Pontiac or Detroit to offer tutorial services. After serious discussion, we reached the decision that tutoring is best done close to home, for several reasons. First is the respect for tutors’ time, the notion that it is best spent with children rather than traveling. Second, we hope that relationships will form between tutors and their children and that they will see one another in their community, rebuilding that network of support around youngsters and heightening a sense of shared community. Tutors often feel stretched with existing job, study, research, and family commitments. Therefore, we try to enable faculty and students the chance to work with schools where their own children attend, at sites located in their neighborhood, or at their work site. Working with the parent community coordinators funded by NSF at Pontiac Owen and Detroit Lessenger Schools, CUOS is providing assistance to help them reach out to their parents and stakeholders to expand existing after-school and during-school tutorial programs. Utilizing the coalition, U-M Family Math and Science program and Michigan State University’s 4-H Extension partners are being tapped to provide training and support for tutors in Washtenaw County, Pontiac, and Detroit. Finally, tutors are encouraged to use the coalition Web site to find fun experiments to do with the children they tutor, to find and use career exploration resources, or to make arrangements for Wizard visits.

• Goal 3: Strategies to Promote Career Exploration. CUOS provided career presentations and tours for children and teens for several years. As a coalition facilitator, CUOS now reaches out to gather, organize, and communicate career exploration opportunities available for children, parents, and educators from the university, from other higher-education entities, and from area businesses. These resources are currently classified on the Web as Career Presentations, Tours, and Job Shadowing.

We believe this effort is critical for several reasons. Children, teens and parents do not know where to go or how to find out about career possibilities within science, math, technology, and engineering fields. Therefore, they have little or no idea what opportunities exist. This, in turn, means children do not have a career goal or an idea of where they are going; nor do they see a reason to take classes or to strive to do well on tests. We believe that higher education and business must come together with strategies to communicate and share the career information they possess.

• Conclusion: CUOS Making a Difference by Collaboration. CUOS is providing leadership to communities for building coalitions in order to leverage more people and resources for children so they may learn science and math and explore careers in related fields. All local and regional stakeholders sharing resources and owning some portion of responsibility for educating youngsters must work together and pool resources and efforts. Too often, the children who have the greatest math and science learning deficiencies are those who have the least access to support and services. CUOS believes our coalition model, Web-site resource clearinghouse, and focus on services for children may be useful and adapted by others.

• Laser-Based Accelerators. High-field science and high-field technology research at the Center has opened up the possibility of developing laser-based accelerators for giga-electron-volt electrons and million-electron-volt ions based on femtosecond laser plasma and wakefield effects. These devices are envisioned as being tabletop systems with the ability to produce charged particle beams that would normally require the use of large, high-energy accelerator systems with associated complex beam-handling systems. Commercial applications of such laser-based systems are wide-ranging and represent a very important technology transfer avenue for the Center. Programs are under way to demonstrate proof of concept and to establish guidelines for the design of practical accelerator devices.

• Lightning Protection Using Light Channeling. Light channeling offers the impressive possibility of creating a conducting path (as if unwinding a conducting wire at the speed of light), at a repetition rate of 10–100 Hz, over a distance of a few hundred meters. An important application is in airport and power plant protection. This technology could replace rockets with attached conducting wires, which are more hazardous to handle because the lightning can trigger as the rocket is on its way down. Rockets are also more expensive, at a few hundred dollars per shot, and restricted in the number of shots. Contacts have been made regarding this through the Electric Power Research Institute (EPRI).

• Precision Micromachining. A new, small spin-off company called MuLex has been established by Xinbing Liu, who is a Center research scientist. Its purpose is to provide consulting for and demonstration of precision micromachining with femtosecond pulses. Work is under way in support of research for IBM and other companies on this subject. A small number of samples has been fabricated for industrial clients using the Center’s lasers under the UDL program. Responding to industrial needs for faster and more accurate measurement of three-dimensional objects such as automotive parts, the Center has come up with a scheme to use femtosecond laser pulses for optical metrology. With the help of U-M’s TMO, practical applicability and marketability are being evaluated.

• Sub-100 fs Lasers. M. Murnane and H. Kapteyn, who recently joined the Center, continue to operate their commercial ultrafast laser business under the name of Kapteyn/Murnane Labs. This enterprise has introduced the following products into the market: (1) a millijoule kilohertz Ti:sapphire amplifier commercialized this year by Excel/Quantronix, and (2) a 15-fs Ti:sapphire laser commercialized and being sold throughout the world by Kapteyn/Murnane Labs. This enterprise will continue to operate from its new Ann Arbor base, maintaining close collaborations with Excel/Quantronix, Union Carbide, and Aculight.

• Master of Engineering Program. The Master of Engineering program has been in place for over a year now and is being examined as a mechanism to increase interaction with industry through graduate student thesis projects that are closely integrated with commercial development programs. Special funding is being sought for this program through various agency mechanisms.

The Visiting Fellows Program has been an unqualified success and we do plan to continue and to expand it in the future. Our goal is to continue to use this program to reach out to the international ultrafast science community through workshops, collaborative visitors, speakers, fellows, and visiting students.

Future workshops can be expected to focus on emerging areas of ultrafast science, such as relativistic plasmas, biology, imaging, or single-cycle pulses.

The Fellows Committee, which makes all major policy decisions about distribution of effort in the program, will continue to rotate so as to reflect the interests of a broad spectrum of science in the Center. In this way we can ensure that the Visitors and Fellows Program can play a lead role in establishing new directions in ultrafast science.

Throughout the proposal we have attempted to clarify the mode of operation of our Center and to illustrate how the research programs selected are those in which the Center mode of research will make the largest impact. In this section we discuss a number of general ways in which a Center mode of research gives a significant "added value" relative to traditional single-investigator funding, and then give specific examples of how this has worked at CUOS .

We believe the principal advantages afforded by Center-style funding to be the following. (1) Large-scale experiments requiring major capital equipment and teams of dedicated researchers clearly require a Center mode of operation. (2) Interdisciplinary projects, involving researchers from widely disparate fields who would be unlikely to be able to pursue risky but potentially revolutionary new ideas, clearly benefit from a Center mode. (3) Outreach programs, including knowledge and technology transfer, K–12 education outreach, and visiting fellows programs, are enabled by Center-style funding (and are difficult if not impossible under single-PI funding). (4) Centers of excellence make it possible to attract top scholars in a field into a single location, which acts as an incubator for new ideas in the field. Some illustrations of how these apply to CUOS are given here.

Center-style projects are intrinsically multidisciplinary and benefit tremendously from Center funding. The principal criteria used in determining which projects are supported by CUOS are that they must be interdisciplinary or collaborative in nature, have the potential of making a major impact in the field, and be suitable for CUOS in that they must utilize its unique capabilities and work at the limits of the technology of ultrafast optics. Indeed, one of the main goals of the Center is to "provide the right tool" for experimenters wishing to break new ground in their field. Once an opportunity is identified, the Center may move quickly to exploit it. Examples of how this works at CUOS abound; we mention just a few here.

Another example is from the field of terahertz optoelectronics, where femtosecond pulses are used to generate and measure electrical wave forms in the terahertz domain. This work was initially motivated by the need for new measurement techniques in high-speed electronics. We now find that there are important new applications of this technology in the measurement of optical and x-ray detectors. This is a prime example of the Center mode of operation, in which two groups, one working on terahertz electronics and one on x-ray pulse generation, can work together to develop an ultrafast x-ray detector.

The educational value of such multidisciplinary research should be emphasized. Students working on such projects must work closely with researchers in other fields. For instance, we have students in plasma physics becoming involved with research in the biomedical area.

Outreach programs are, of course, a major component of Center operation. For example, the technology transfer program is vigorously pursued under the direction of an Associate Director for Industrial Liaison. The program has had considerable success, involving interactions with numerous companies, and in the introduction of at least nine commercial products in the marketplace based on CUOS research. Successful technology transfer requires the "right attitude," in which the scientist responsible for a marketable idea works closely with industry to move the idea from the laboratory to the prototype stage; simply having a good idea is not enough. A noteworthy benefit of having such a program in a university-based center is that students have the inspirational experience of working with industry to carry their ideas through to fruition.

CUOS is also heavily involved in educational outreach, including visiting undergraduate summer researchers and K–12 outreach programs such as tutoring and summer science programs (with a special emphasis on targeting critical age groups). Such programs are extremely valuable, are strongly motivated by the presence of the Center, and it is mainly through NSF-CUOS funding that resources are available for them.

CUOS also acts as an international center for the field of ultrafast science through its Fellows program. This program has attracted literally hundreds of visiting scientists through the Visiting Fellows program, has cost-shared numerous sabbatical visitors and research Fellows, has sponsored lively and stimulating workshops on special topics, and has generally had a major impact on Center research. The Fellows program helps in a very significant way to make CUOS a national resource in ultrafast optical science; such programs are only possible within the context of a Center mode of funding and operation.

The success of the Center can be seen by the number of centers in the world which have been or will be created after the CUOS model, including those in France (LOA), Japan (Advanced Photon Source in Kansai), Canada (at the NRC), and Sao Paulo, Brazil. These new centers will follow the CUOS example, exploiting the dual aspect of short pulses in the time and high-intensity regime, and integrating research, technology transfer, and education. The success of the Center can also be measured in its ability to attract top scholars and to create an important ultrafast community on and around campus. With the Center, new faculty have been attracted to Michigan, including H. Kapteyn, M. Murnane, and M. Islam in Electrical Engineering and Computer Science, P. Berman in Physics, R. Sension in Chemistry, and T. Juhasz and R. Kurtz in the Kellogg Eye Center. Outside the campus the Center has spun off and attracted companies which are now employing more than 50 people making ultrafast products, such as femtosecond lasers , laser components, and ultrafast detectors.

Without a doubt, the creation of a Science and Technology Center based on the theme of ultrafast optical science has had a tremendous impact on the field, on the research and educational programs of the University of Michigan, on industries associated with ultrafast optics, and on the students and scientists who have had the opportunity to work at CUOS. The tremendous growth and success of CUOS in its first six years is its own best testament to the value of the Center mode of funding and operation.

The strategic directions of the Center are established through a process of review and consensus. Important components of the review process are the External Advisory Board and the Technical Advisory Committee, which are described below. In addition, each week there is a staff meeting at which any Center investigator may come to discuss coordination issues with the directors.

During the past five years, CUOS has strengthened its program by adding new faculty T. Norris, R. Sension, R. Kurtz, M. Murnane, and H. Kapteyn. Professors Murnane and Kapteyn came to the Center with six students and two postdoctoral fellows, as well as their entire laboratory, from Washington State University. They have begun to play a major role in determining the strategic scientific directions of the Center.

Once a year, the Executive Committee members meet with our External Advisory Board, composed of leaders from academia, industry, and national laboratories [see Appendix F]. After consultation with the advisory board the directors carry out the administrative directions and monitor day-to-day activities.

One important body of CUOS is its Technical Advisory Committee (TAC), which has been chaired by Professor Norris. It is composed of the Director, the Associate Directors, and the five area coordinators, plus one scientist from each area. The TAC meets twice a year to discuss scientific progress, directions, and Center policies. Decisions regarding resource allocation emanate from the TAC recommendations. The TAC evaluates projects according to the criteria of scientific impact, Center suitability, cooperation, multidisciplinarity, and student involvement.

This program is administered by P. Bucksbaum, Associate Director for Science. He is assisted by a committee whose current members are Profs. T. Norris, R. Sension, and M. Murnane.

In order to foster communication, promote multidisciplinary activities, and share equipment, the center is consolidated under one roof. Through an NSF infrastructure grant that was cost-shared with the university, we have just completed the renovation of 10,000 sq ft of laboratory space, nearly doubling the Center laboratory area. Once per week we have a well-attended student seminar where Center personnel describe their research in progress. This seminar, which emphasizes student participation, provides a forum for researchers to become familiar with activities outside their own particular areas. During the academic year we have as part of our Fellows program an Ultrafast Science seminar where the best scientists in our field are invited to speak.

P. Pronko is charged with integrating an industrial component into the educational and research activities at CUOS. We encourage industrial associates to establish a physical presence at the Center, and to participate broadly with graduate students and research scientists in Center research.

The education and outreach programs are directed by Professor H. Winful, with the assistance of an education coordinator. An Education Advisory Committee provides input on new initiatives and student recruitment.

CUOS has already established several important new scientific directions which can be expected to continue beyond the 11-year "sunset" of the STC. Laser acceleration, ultrafast vuv and x-ray light sources, and ultrafast medical applications have already been identified as areas that should attract major independent funding in the future. In addition, we expect that ultrafast science and technology will continue to spring from the collaborative activities that are best carried out in a "Center," however it is constituted. One of our major management challenges in the next three years will be to secure means to continue these activities, which have served the international ultrafast community so well.

A. Braun, G. Korn, X. Liu, D. Du, J. Squier, and G. Mourou, "Self-Channeling of High-Peak-Power Femtosecond Laser Pulses in Air," Opt. Lett. 20, 73-75 (1995).

C. Rouyer, É. Mazataud, I. Allais, A. Pierre, S. Seznec, C. Sauteret, G. Mourou, and A. Migus, "Generation of 50-TW Femtosecond Pulses in a Ti:sapphire/Nd:glass Chain," Opt. Lett. 18, 214-216 (1993)

D. Strickland and G. Mourou, "Compression of Amplified Chirped Optical Pulses," Opt. Commun. 56, 219-221 (1985).

M. Pessot, P. Maine, G. Mourou, "1000 Times Expansion/Compression of Optical Pulses for Chirped Pulse Amplification," Opt. Commun. 62, 419-421 (1987).

P. Maine, D. Strickland, P. Bado, M. Pessot, and G. Mourou, "Generation of Ultrahigh Peak Power Pulses by Chirped Pulse Amplification," IEEE J. Quantum Electron. 24, 398-403 (1988).

J.A. Valdmanis, G. Mourou, and C.W. Gabel, "Subpicosecond Electrical Sampling," IEEE J. Quantum Electron, 19, 664 (1983)

G. Mourou and S. Williamson, "Picosecond Electron Diffraction," Appl. Phys. Lett. 41, 44-45 (1982).

Jean Claude Kieffer, INRS-Energié, Quebec CANADA

Kent Wilson, University of California at San Diego, USA

Arnold Migus, Ecole Polytechnique, ENSTA, FRANCE

Phillip Sprangle, Naval Research Laboratory

Francois Salin, Ecole Polytechnique, ENSTA, FRANCE

Georg Korn, Max Born Institute, GERMANY

H.G. Winful, J.H. Marburger, and E. Garmire, "Theory of bistability in nonlinear distributed feedback structures," Appl. Phys. Lett. 35, 376 (1979)

H.G. Winful, "Nonlinear reflection in cholesteric liquid crystals: mirrorless optical bistability," Phys. Rev. Lett. 49, 1179 (1982).

H.G. Winful and S.S. Wang, "Stability of phase locking in coupled semiconductor laser arrays," Appl. Phys. Lett. 53, 1894 (1988).

D.T. Walton and H.G. Winful, "Passive mode locking with an active nonlinear directional coupler: positive group velocity dispersion," Optics Lett., 18, 720 (1993).

B.A. Malomed and H.G. Winful, "Stable solitons in two-component active systems," Phys. Rev. E 53, 5365 (1996).

University of Michigan Date of Birth: January 14, 1953

2071 Randall Lab Place of Birth: Grinnell, Iowa

Ann Arbor, MI 48109-1120 (313) 764-4348

A.B. magna cum laude in Physics, 1975, Harvard College, Cambridge, MA 02138.

Ph.D. (1980) and M.A. (1978) in Physics from the University of California, Berkeley, CA 94720. Thesis advisor: Eugene Commins; Thesis Topic: Parity Non-Conservation in Atomic Thallium.

8/80-11/82 Post-doctoral research at AT&T Bell Laboratories, Holmdel, NJ 07733, and at Lawrence Berkeley Laboratories, Berkeley, CA 94720.

11/82-8/90 Principal Investigator Member of Technical Staff, Physics Research Division, AT&T Bell Laboratories, Murray Hill, NJ 07974.

1/89-8/90 Adjunct Associate Professor of Applied Physics, Columbia University, New York, NY.

9/90-present: Professor of Physics, University of Michigan.

2/91-present: Associate Director for Science, NSF Center for Ultrafast Optical Science.

Fellow of the American Physical Society, 1990.

Fellow of the Optical Society of America, 1995.

Miller Fellow, 1996

Guggenheim Fellow, 1996-97

Distinguished Faculty Achievement Award, 1996

National Science Foundation Graduate Fellowship, 1975-78.

NATO Post-doctoral Fellow, 1981 (resigned to join Bell Labs, 1981)

C. Raman, C.W.S. Conover, C.I. Sukenik, and P. H. Bucksbaum,"Ionization of Rydberg Wavepackets by Sub-Picosecond, Half-Cycle Electromagnetic Pulses," Physical Review Letters 76, 2436 (1996).

D. W. Schumacher, J. H. Hoogenraad, Dan Pinkos, P. H. Bucksbaum, "Programmable Cesium Rydberg Wavepackets," Physical Review A 52, 4719-26 (1995).

R. R. Jones and P. H. Bucksbaum, "Rydberg Atoms Irradiated by Ultra-short Terahertz Pulses,"

Comments on Atomic and Molecular Physics 30, 347 (1995).

R. R. Jones, N.E. Tielking, D. You, C. Raman, and P.H. Bucksbaum,"Ionization of Oriented Rydberg States by Sub-Picosecond Half-Cycle Electromagnetic Pulses," Phys. Rev. A

51, R2687 (1995).

R.R. Jones, D.W. Schumacher, T.F. Gallagher, and P.H. Bucksbaum,"Bound-State Interferometry Using Incoherent Light," J. Phys. B: At. Mol. Opt. Phys. 28 L405 (1995).

R.R. Jones, C. S. Raman, D. W. Schumacher, and P. H. Bucksbaum, "Ramsey interference in strongly driven Rydberg Systems," Physical Review Letters 71, 2575 (1993).

R.R. Jones, D. You, and P.H. Bucksbaum, "Ionization of Rydberg Atoms by Sub-Picosecond Half-Cycle Electromagnetic Pulses," Physical Review Letters 70, 1236 (1993).

D. You, R. R. Jones, D.R. Dykaar, and P.H. Bucksbaum, "Generation of High-Power Half-Cycle 500 Femtosecond Electromagnetic Pulses," Optics Letters 18, 290 (1993).

R.R. Jones and P.H. Bucksbaum, "Ionization Suppression of Stark States in Intense Laser

Fields," Physical Review Letters 67, 3215, (1991).

B.I. Greene, J.F. Federici, D.R. Dykaar, R.R. Jones, and P.H. Bucksbaum,"Interferometric Characterization of 160 fsec Far-Infrared Light Pulses," Applied Physics Letters 59, 893, (1991).

M. Bashkansky, Columbia University Physics, Ph.D. 1988

A. Zavriyev, Columbia University Applied Physics, Ph.D. 1993

U. Mohideen, Columbia University Physics, Ph.D. 1993

Douglass Schumacher, University of Michigan, Ph.D. 1995

Donne You (Defending April 1996), Marcus Hertlein Subrata Dutta (Electrical Engineering)

Frederick Weihe, Chandra Raman, Michael Lim, Madeline Naudeau

John Caraher, Thomas Weinacht

Yuan Wang Liao (EECS), Tom Sosnowsky (EECS), Charles Leggett, Gerald L. Vossler (EECS)

R. Garisto (1993), T. Steiger (1993), Ali Al-Ramadhan (1994), Xingbing Liu (1994)

Heewon Lee (Chemistry) (1995), Scott Cheng (Appl. Phys.) (1995), D. Du (1996)

Jeffrey Bokor, University of California at Berkeley

C. L. Chin, University of Laval

Ralph S Conti, University of Michigan

Louis DiMauro, Brookhaven National Laboratory

Douglas Dykaar, AT&T Bell Laboratories

Joe Eberly, University of Rochester

Richard R. Freeman, AT&T Bell Laboratories

George Gibson, AT&T Bell Laboratories

Ben Greene, AT&T Bell Laboratories

Jan Hoogenraad, FOM Institute (AMOLF), Amsterdam

Robert R. Jones, University of Virginia

Ken Kulander, LLNL

Macek Lewenstein, CEA Saclay

Howard Milchberg, University of Maryland

Umar Mohideen, AT&T Bell Laboratories

Gerard Mourou, University of Michigan

Harm Muller, FOM Institute for Atomic and Molecular Physics

M. Saeed, Brookhaven National Laboratory

Ken Schafer, Lawrence Livermore National Laboratory

Peter Shkolnikov, Johns Hopkins University

H.W.K. Tom, AT&T Bell Laboratories

Donald J. Umstadter, University of Michigan

B. van Linden van den Heuvell, Univ. of Amsterdam

Kent Wilson, University of California at San Diego

B. Yang, Brookhaven National Laboratory

A. Zavriyev, Columbia University and University of Michigan

University of Michigan FAX: (313) 763-4876

Ann Arbor, MI 48109-2099 E-mail:kapteyn@eecs.umich.edu

__________________________________________________________________________________

J. Zhou, J. Peatross, M.M. Murnane, H.C. Kapteyn, "Enhanced High-Harmonic Generation using 26 Femtosecond Laser Pulses", Physical Review Letters 76, 752 (1996).

J. Zhou, C.P. Huang, M. M. Murnane, and H. C. Kapteyn, "Amplification of 26 fs, 2 TW pulses near the gain narrowing limit in Ti:sapphire," Optics Letters 20, 64 (1995).

S. Backus, J. Peatross, M.M. Murnane, and H.C. Kapteyn, "Ti:sapphire Amplifier Producing Millijoule-Level, 21 fs Pulses at 1 kHz," Optics Letters 20, 2000 (1995).

H.C. Kapteyn and M.M. Murnane, "Femtosecond lasers: the Next Generation," Optics and Photonics News, 5 (3), 20 (1994).

H. C. Kapteyn, "Photoionization-Pumped X-Ray Lasers using Ultrashort-Pulse Excitation," Applied Optics 31, p.4931 (1992).

M.T. Asaki, C.P. Huang, D. Garvey, J. Zhou, H.C. Kapteyn, M.M. Murnane, "Generation of 11-fs pulses from a self-mode-locked Ti:sapphire laser," Optics Letters 18, 977 (1993).

G. Taft, A. Rundquist, M. Murnane, H. Kapteyn, K. DeLong, R. Trebino, I. Christov, "Ultrafast optical waveform measurements using Frequency Resolved Optical Gating," Opt. Lett. 20, 743 (1995).

H. C. Kapteyn and M. M. Murnane, "Relativistic Pulse Compression," J. Opt. Soc. Am. B 8, 1657 (1991).

Z. Chang, A. Rundquist, J. Zhou, M. Murnane, H. Kapteyn, X. Liu, B. Shan, J. Niu, M. Gong, X. Zhang, "Demonstration of a Sub-Picosecond X-Ray Streak Camera", to be published in Applied Physics Letters.

S. Backus, H.C. Kapteyn, M.M. Murnane, D. Gold, H. Nathel, and W. White, "Self-Induced Plasma Shuttering using a Regenerating Fluid Target", Optics Letters 18, 134 (1993).

Dr. Rick Trebino and Dr. Ken DeLong, Sandia National Laboratory

Prof. Ivan Christov, Sofia University, Bulgaria

Dr. J.C. Mialocq and Dr. S. Pomeret, French Commissariat a l'Energie Atomique, Saclay, France

Dr. Milan Kokta and Dr. George Venikouas, Union Carbide Crystal Products

Dr. Howard Nathel and Dr. Mordecai Rosen, Lawrence Livermore National Laboratory

Dr. Roy Mead, Aculight Corporation

Dr. Sten Tornigard, Excel/Quantronix

Professor Roger Falcone

Advisees in past 5 years (with Prof. Margaret Murnane):

Postdoctoral: Dr. Justin Peatross, Dr. Zenghu Chang, Dr. Jaiwen Fan, Dr. Chip Durfee

Ph.D.: Dr. Jianpig Zhou, Dr. Chung-Po Huang, Sterling Backus, Greg Taft, Kendall Read, Andy Rundquist, Erik Zeek, Haiwen Wang, Kira Maginnis, Florian Blonigen

M.S.: Melanie Asaki, Andy Sackreiter, Donna Argento, Chengyu Shi, John McIntosh

Undergraduate: Nicole Dawson, Colette Sackstedter, Alisa Ellingson, Chris Baldwin, Chris Wark, Larry Roy, Marie Tripp

Ultrafast Science Laboratory phone (313)764-9269

University of Michigan fax (313)763-4876

2200 Bonisteel Blvd. e-mail: tnorris@eecs.umich.edu

Ann Arbor, MI 48109-2099

Ph.D., Physics, University of Rochester, Rochester, NY, 1989.

M.A., Physics, University of Rochester, Rochester, NY, 1984.

B.A., Physics (with Highest Honors), Oberlin College, Oberlin, Ohio, 1982.

Center for Ultrafast Optical Science

2200 Bonisteel

IST Building

University of Michigan

Ann Arbor, MI 48109

(313) 763-0575

1982 Diploma in Physics, JATE University of Szeged, Hungary

1986 Ph.D. in Physics, JATE University of Szeged, Hungary

1981 - 1982 Research Assistant, Central Research Institute for Physics, Budapest, Hungary

1982 - 1985 Research Assistant, Department of Experimental Physics, Technical University of

Budapest, Hungary

1985 - 1986 Assistant Professor, Department of Experimental Physics, Technical University of

Budapest, Hungary

1987 - 1987 Research Assistant, Laboratory for Laser Energetics, University of Rochester

1987 - 1990 Postgraduate Researcher, Department of Physics, University of California, Irvine

1990 - 1994 Assistant Research Physicist, Department of Physics, University of California, Irvine

1994 - 1994 Visiting Professor, Department of Applied Physics and German Cancer Research

Institute, University of Heidelberg, Germany

1994 - 1995 Lecturer, Department of Physics, University of California, Irvine

1996 - Present Visiting Scientist, Center for Ultrafast Optical Science, University of Michigan

1990 - 1994 Senior Research Scientist, Intelligent Surgical Lasers., Inc., San Diego, California

1991 - 1995 US-Hungarian Science and Technology Fund support

American Physical Society

Association for Research in Vision and Ophthalmology

1985 - 1986 Lectures on classical mechanics and electromagnetic theory, Technical University

of Budapest

1989 - 1993 Lectures on laser physics, University of California, Irvine

1994 Lectures on medical applications of lasers, University of Heidelberg (Visiting Scholar)

1994 - 1995 Lectures on physics (for biology majors and medical students), University of

California, Irvine

T. Juhasz, X.H. Hu, L. Turi, and Z. Bor, "Dynamics of Shock Waves and Cavitations Generated by Picosecond Laser Pulses in Corneal Tissue and Water," Lasers in Surgery and Medicine 15, 91 (1994).

M.S. Habib, M.G. Speaker, R. Kaiser, and T. Juhasz, "Myopic Intrastromal Photorefractive Keratectomy with the Nd:YLF Picosecond Laser in the Cat Cornea," Archives of Opthalmology 113, 499 (1995).

T. Juhasz, G.A. Kastis, C. Suarez, Z. Bor and W.E. Bron, "Time-Resolved Observations of Shock waves and Cavitation Bubbles Generated By Femtosecond Laser Pulses in Corneal Tissue and Water," Lasers in Surgery and Medicine 19, 23-31 (1996).

L. Turi, and T. Juhasz, "Diode-Pumped Nd:YLF All-In-One Laser," Optics Letters 20, 1541 (1995).

F. Loesel, M.H. Niemz, J.F. Bille and T. Juhasz, "Laser-Induced Optical Breakdown and Hard and Soft Tissues: Theory and Experiment," In press IEEE Journal of Quantum Electronics.

C. Suarex, W.E. Bron, and T. Juhasz, "Dynamics and Transport of Electronic Carriers in Thin Gold Films," Physical Review Letters, 75, 4536 (1995).

L. Turi, and T. Juhasz, "High-Power Longitudionally Diode-Pumped Nd:YLF Regenerative Amplifier," Optics Letter 20, 154 (1995).

T. Juhasz, H.E. Elsayed-Ali, C. Suarez, G.O. Smith, and W.E. Bron, "Direct Measurements of the Transport Nonequilibrium Electrons in Gold Films with Different Crystal Structures," Physical Review B 48, 15488 (1993).

X.H. Hu, and T. Juhasz, "Experimental Study of Corneal Ablation with Picosecond Laser Pulses at 211 and 263 Nanometers," Lasers in Surgery and Medicine 18, 373-380 (1996).

T. Juhasz, and W.E. Bron, "Subpicosecond Resolved Polariton Decay," Physical Review Letters 63, 2385 (1989).

University of Michigan

Kellogg Eye Center

Ann Arbor, MI

(313) 763-3727

A.B., Biochemical Science, Harvard University, Cambridge, MA (1985)

M.D., Medicine, University of California, San Diego, CA (1990)

Internship, Medicine, Mount Sinai, School of Medicine, New York, NY (1991)

Residency, Ophthalmology, University of Michigan, Ann Arbor, MI (1994)

Fellowship, Vitreoretinal Diseases & Surgery, University of Illinois, Chicago, IL (1995)

7/95 - Present Assistant Professor Ophthalmology

Research to Prevent Blindness, 1995

Morton F. Goldberg Vitreoretinal Fellowship Award, 1995

Resident Research Award, University of Michigan, Department of Ophthalmology, 1994

Michigan

Illinois

D. Du, J. Squier, R. Kurtz, V. Elner, X. Liu, G. Guttmann, G. Mourou, "Damage threshold as a function of pulse duration in biological tissue," Ultrafast Phenomena IX, Springer Series in Chemical Physics, Vol 60, page 254. P. Barbara, W. Knox, G. Mourou, and A. Zewail, eds., Springer-Verlag, Berlin (1994).

R.M. Kurtz, J.A. Squier, V.M. Elner, D. Du, X.B. Liu, A. Sugar, G. Mourou, "Nonlinear effects and potential surgical advantages of femtosecond lasers," Invest Opthalmol Vis Sci 35, 1786 (1994).

D. Du, X. Liu, J. Squier, V. Elner, R.M. Kurtz, G. Mourou, "Laser induced breakdown in biological tissues with ultrashort pulsewidths," Laser in Surgery and Medicine 6, 5 (1994)

X. Liu, V.M. Elner, R.M. Kurtz, "Fluence Threshold for Corneal Ablation as a function of pulsewidth," Invest. Ophth. Vis Sci 37, 1489 (1996)

R.M. Kurtz, X. Liu, T. Juhasz, V.M. Elner, "Tissue Ablation as a function of laser pulsewidth," IEEE/LEOS Advanced Applications of Lasers and Material Proceedings (1996).

J.R. Polansky, R.M. Kurtz, J.A. Alvarado, R.N. Weinreb, M.D. Mitchell, "Eicosanoid production and glucocorticoid regulatory mechanisms in cultured human trabecular cells," In: Bito, LZ and Stjernachanta J, eds. Ocular Effects of Prostaglandins and Other Eicosanoids. New York: Alan R. Liss, Inc., 113,-138 (1989)

J.R. Polansky, R.M. Kurtz, D.J. Fauss, R.Y. Kim, E. Bloom, "In vitro correlates of glucocorticoid effects on intraocular pressure," In: G.K. Krieglstein, ed. Glaucoma Update IV Berlin: Springer-Verlag, 20-29 (1991)

J.R. Polansky, R.M. Kurtz, T.D. Nguyen, W.D. Huang, J.A. Alvarado, "In vitro model for steroid effects on IOP: characterization of HTM protein/glycoprotein changes and molecular cloning approaches," ARVO abstract. Invest Opthalmol Visual Sci 31, 377 (1990)

R.M. Kurtz, V.M. Elner, R.M. Strieter, S.L. Kunkel, Z.M. Bian, S.G. Elner, "Inhibition of cytokine-stimulated RPE cell chemokines by Dexamethasone and Cyclosporin A," Submitted Invest Ophthalmol Vis Sci.

S.G. Elner, V.M. Elner, Z.M. Bian, R.M. Kurtz, R.M. Strieter, S.L. Kunkel, "T-lymphocyte secretions induce human retinal pigment epithelial cell interleukin-8 and monocyte chemotactic protein-1," Submitted Invest Ophthalmol Vis Sci March, 1996.

BIOGRAPHICAL SUMMARY

Principal Investigator: Emmett N. Leith

Experience: Emmett N. Leith is the Schlumberger Professor of Electrical Engineering at the University of Michigan, where he has been since 1952. He has worked primarily in the areas of optical processing, holography, interferometry, and synthetic aperture radar.

Education: 1978 - Ph.D., Electrical Engineering, Wayne State University

1952 - M. S., Physics, Wayne State University

1949 - B. S., Physics, Wayne State University, with High Distinction (the highest possible category )

Honors and Awards:

National Medal of Science, 1980

Honorary Member, Engineering Society of Detroit, 1980

National Academy of Engineering, 1980

Russel Lecturer, 1981

Dennis Gabor Award, SPIE, 1983

Robert Pole Lecturer, Optical Society of America, 1985

Herbert Ives Medal, Optical Society of America, 1985

Fellow, Engineering Society of Detroit, 1987

Engineering Hall of Fame, Wayne State University, 1987

Gold Medal of SPIE, 1990

He is listed in American Men of Science and Who's Who in America.

He is the author of numerous journal articles and contributions to books.

Professional Societies:

Fellow, Optical Society of America,

Fellow, IEEE

Fellow, SPIE

National Academy of Engineering

1. E. Leith, C. Chen, H. Chen, Y. Chen, D. Dilworth, J. Lopez, J. Rudd, P.-C. Sun, J. Valdmanis and G. Vossler, "Imaging through scattering media with hologram," J. Opt. Soc. Am. A., 9, 1148-1153 (1992).

2. Y. Chen, H. Chen, D. Dilworth, E. Leith, J. Lopez, M. Shih, P.-C. Sun and G. Vossler, "Evaluation of holographic methods for imaging through biological tissue," Appl. Opt., 32, 4330-4336 (1993).

3. P.-C. Sun and E. N. Leith, "Broad-source image plane holography as a confocal imaging process," Appl. Opt., 33, 497-602 (1994).

4. M. Shih and E. Leith, "Spatial filtering of first-arriving light," Appl. Opt. 34, 1310-1313 (1995).

5. P. Naulleau, D. Dilworth, E. Leith and J. Lopez, "Detection of moving objects embedded within scattering media by use of speckle methods," Opt. Lett., 20, 498-500 (1995).

6. E. N. Leith, C. Chen and A. Cunha, "Image formation through inhomogeneities," SPIE Conference, Application of Optical Engineering, Proc,. Vol 139C, 80-84 (Sept. 27-28, 1990).

7. E. Leith, P. Lyon and H. Chen, "Imaging problems with femtosecond-pulse holography," J. Opt. Soc. Am. A., 8, 1014-1018 (1991).

8. E. Leith, H. Chen, Y. Chen, D. Dilworth, J. Lopez, R. Masri, J. Rudd and J. Valdmanis, "Electronic holography and speckle methods for imaging through tissue using femtosecond gated pulses," Appl. Opt., 30, 4204 (1991).

9. P.-C. Sun and E. N. Leith, "Superresolution by spatial-temporal encoding methods," Appl. Opt. 31, 4857-4862 (1992).

10. P. Naulleau and E. Leith, "Stretch, time lens, and incoherent time imaging," Appl. Opt., 34, 4119-4128 (1995).

There are no collaborators other than those already cited in the publication list.

Dr. Marian Shih

Dr. Eric Arons

Dr. Pang-Chen Sun

Dr. Ye Chen

Dr. Chaiohsiang Chen

N/A

Xinbing Liu Assistant Research Scientist

Univeristy of Mighigan Tel: (313) 936-4805,

Center for Ultrafast Optical Science Fax: (313) 763-4876

2200 Bonisteel Blvd. e-mail: monkey@umich.edu

Ann Arbor, MI 48109-2099

Univ. of Bucharest, Romania M.S. 1985 Physics

Univ. of Michigan, Ann Arbor, MI Ph.D. 1994 Applied Physics

Univ. of Michigan, Ann Arbor, MI Post-doctoral 1994-95 Optics

Assistant Research Scientist, 1995 -- present, Center for Ultrafast Optical Science, University of Michigan. Current research activities include:

Laser micromachining and processing with femtosecond laser pulses.

Medical laser project. Applications of ultrafast lasers in surgery, particularly in ophthalmology. This program is being carried out at CUOS in collaboration with the Department of Ophthalmology at the Medical School of the University of Michigan. The goal is to develop a laser surgery procedure for the treatment of glaucoma using ultrafast lasers.

Compact, ultrafast laser development. The goal of the project is to develop novel diode laser-pumped, efficient, reliable, multi-watt average power femtosecond laser systems for medical and industrial applications. Research involves all aspects of a chirped-pulse amplification laser system: laser materials, cavity design, pumping source and pumping geometry, compact stretcher and compressor design.

Propagation of intense femtosecond laser pulses.

Postdoctoral Research Fellow, Center for Ultrafast Optical Science, University of Michigan, 1994 -- 1995

Micromachining with ultrashort laser pulses.

Femtosecond lasers in medical applications.

Propagation of intense femtosecond lasers.

Development of advanced ultrafast solid-state laser systems.

High intensity, short pulse laser-matter interactions, including

solid targets and in gases.

Graduate Student Research Assistant, University of Michigan, 1988 -- 1994.

High intensity, short pulse laser-matter interactions, including solid targets and in gases.

Computer modeling of laser-plasma interactions

Laser-induced breakdown in dielectric materials and biological tissues.

Ultrafast solid-state lasers.

Technical Staff, Institute of Modern Optics, Nankai University, China, 1985 -- 1987.

Optical information processing, Fourier optics.

X. Liu, D. Du, A.-C. Tien, and G. Mourou, "Laser micromachining with ultrashort pulses," Conference on Lasers and Electro-Optics (1996)

X. Chen, X. Liu, W. Laotshaw, "Machining with Ultrafast Laser Pulses," International Conference on Applications of Lasers and Electro-Optics (1996)

X. Liu, R. Kurtz, and V. Elner, "Fluence threshold for human corneal ablation as a function of laser pulse widths," ARVO (1996)

A. Braun, X. Liu, and G. Mourou, "A diode-pumped Nd:glass regenerative amplifier for sub-picosecond microjoule level pulses," submitted to Applied Optics.

G. Mourou, X. Liu, et al, "Method for controlling configuration of laser induced breakdown and

ablation," International Patent Application No. PCT/US95/03863, International Publication No. WO 95/27587 (1995)

D. Du, X. Liu, and G. Mourou, "Reduction of multi-photon ionization in dielectric due to collision,"submitted to Applied Physiscs B.

J. Workman, A. Maksimchuk, X. Liu, U. Ellenberger, J. S. Coe, C.-Y. Chien, and D. Umstadter, "Picosecond soft X-ray source from subpicosecond-laser-produced plasmas,

J. Opt. Soc. Am. B vol. 13, 125 (1996)

X. Liu, R. Wagner, A. Maksimchuk, E. Goodman, J. Workman, D. Umstadter, and A. Migus, "Nonlinear temporal diffraction and frequency shifts resulting from pulse shaping in chirped-pulse amplification systems," Optics Letters, vol. 20, 1163 (1995)

J. Workman, A. Maksimchuk, X. Liu, U. Ellenberger, J. S. Coe, C.-Y. Chien, and D. Umstadter, "Control of bright picosecond x-ray emission from intense subpicosecond

laser-plasma interactions," Phys. Rev. Lett. vol. 75, 2324 (1995)

None.

Graduate advisor: Gerard Mourou

Post-graduate advisor: Gerard Mourou

Electr. Engin. and Comp. Sci. Dept.

1006 IST Bldg.

University of Michigan, Ann Arbor, MI 48109-2099

Moscow Physical-Engineering Institute, Moscow, Russia, Physics of Solid State, M.S. (1979).

P. N. Lebedev Physics Institute of the Russian Academy of Sciences, Moscow, Russia, Physics and Mathematics, Ph.D., (1991).

Thesis: The method of active quasi-monochromatic x-ray diagnostic of laser-produced plasmas

07/1979 - 12/1992: Engineer, Junior Scientist, Researcher, P. N. Lebedev Physics Institute, Moscow.

12/1992 - 12/1994: Visiting Associate Research Scientist, Electrical Engineering and Computer Science Department, University of Michigan.

01/1995 - 01/1996: Associate Research II in Engineering, Electrical Engineering and Computer Science Department, University of Michigan.

02/1996- : Assistant Research Scientist, Electrical Engineering and Computer Science Department, University of Michigan.

D. Umstadter, S.-Y. Chen, A. Maksimchuk, G. Mourou, and R. Wagner, "Nonlinear optics in relativistic plasmas and laser wakefield acceleration of electrons," Science (accepted for publication, (1996).

A. Maksimchuk, M. Kim, J. Workman, G. Korn, D. Du, J. Squier, D. Umstadter, G. Mourou "Signal averaging x-ray streak camera with picosecond jitter," Rev. Sci. Instrum. 67, 697 (1996).

J. Workman, A. Maksimchuk, X. Liu, U. Ellenberger, J. S. Coe, C.-Y. Chien and D. Umstadter "Control of bright picosecond x-ray emission from intense sup-picosecond laser-plasma interaction," Phys. Rev. Lett. 75, 2324 (1995).

X. Liu, R. Wagner, A. Maksimchuk, E. Goodman, J. Workman, D. Umstadter, A. Migus "Nonlinear temporal diffraction and frequency shifts resulting from pulse shaping in chirped-pulse amplification system," Opt. Lett. 20, 1163 (1995).

Z. Jiang, J. C. Kieffer, J. P. Matte, M. Chaker, O. Peyrusse, D. Gilles, G. Korn, A. Maksimchuk, S. Coe, G. Mourou "X-ray spectroscopy of hot solid density plasmas produced by subpicosecond high contrast laser pulses at 1018-1019 W/cm2," Phys. Plasmas 2, 1702 (1995).

A. Maksimchuk, J. Workman, X. Liu, et al. "Bright Picosecond X-Rays from Subpicosecond Laser Plasma Interactions," X-Ray Lasers 1994, Amer. Inst. of Physics Conf. Proc. No.332, D.E.Edler and D.Matthews, eds. (AIP Press, New York, 1994), pp.473-477.

M. J. Lamb, M. P. Kalashnikov, M. H. Key, A. M. Maksimchuk e.a. "X-ray monochromatic images of laser implosion" in Proceedings of the 21-st European Conference on Laser-Matter Interaction, Warsaw, Poland, P-37, (1991)

K. Goetz, M. P. Kalashnikov, A. M. Maksimchuk e.a. "Technique and methods of laser plasma diagnostics by X-ray multicharged ion spectra" Proceeding of Lebedev Physical Institute Academy of Sciences of the USSR, 203, Moscow, Nauka, 42 (1990). (in Russian)

A. V. Rode, A. M. Maksimchuk, G. V. Sklizkov e.a. "Measurement of X-ray spectral lines wavelength by using two Bragg reflection" Journ. of X-ray Science and Technology, 2, 149 (1990).

A. V. Rode, A. M. Maksimchuk, G. V. Sklizkov e.a. "Intensity measurements of quasi-monochromatic X-ray beam formed by a spherically bent crystal" Opt.Commun., 77, pp.163-166, (1990)

Michael Downer

Robin Marjoribanks

Y. Liu, G.A. Garrett, A. Frenkel, J.F. Whitaker, S. Fahy, C. Uher and R. Merlin, "Impulsive Light Scattering by Coherent Phonons in LaA10: Disorder and Boundary Effects", Phys. Rev. Lett. 75, 334-337 (1995).

S. Fahy and R. Merlin, "Reversal of Ferroelectric Domains by Ultra-short Optical Pulses", Phys. Rev. Lett. 73, 1122 (1994).

"Data Storage Using Pulsed Optical Domain Reversal", U.S. Patent No. 5, 477, 519 (1995).

S. Murugkar, R. Merlin, A. Botchkarev, A. Salvador and H. Morkoc,"Second Order Raman Spectroscopy of the Wurtzite Form of GaN", J. Appl. Phys. (Communications) 77, 6042-6043 (1995).

S.H. Kwok, R. Merlin, W.Q. Li and P.K. Bhattacharya, "Raman Scattering from Heavily-Doped (311) GaAs:Si Grown by Molecular Beam Epitaxy", J. Appl. Phys. 72, 285-286 (1992).

J. Kastrup, R. Klann, H.T. Grahn, K. Ploog, L.L. Bonilla, J. Gal'an, M. Kindelan, M. Moscoso and R. Merlin, "Self-Oscillations of Domains in Doped GaAs-AlAs Superlattices", Phys. Rev. B 52, 13761-13764 (1995).

F. Nori, R. Merlin, S. Haas, A. Sandvik and E. Dagotto, "Magnetic Raman Scattering in Two-Dimensional Spin-1/2 Heisenberg Antiferromagnets: Spectral Shape Anomaly and Magnetostrictive Effects", Phys. Rev. Lett. 75, 553-556 (1995).

R. Merlin, "Rotational Anomalies of Mesocopic Rings", Phys. Lett. A 181, 421 (1993).

S.H. Kwok, H.T. Grahn, K. Ploog and R. Merlin, "Giant Electro-Pleochroism in GaAs-(Al,Ga)As Heterostructures: The Quantum-Well Pockels Effect", Phys. Rev. Lett. 69, 973 (1992).

"Quasiperiodic Layered Structures", U.S. Patent No. 4, 955, 692 (1990)

A. Pinczuk

Bradford G. Orr, University of Michigan

Duncan G. Steel, University of Michigan

E. Dagotto

S. Fahy

L.L. Bonilla

J. Gal'an

E. Schoell

University of Michigan FAX: (313) 763-4876

Ann Arbor, MI 48109-2099 E-mail:murnane@eecs.umich.edu

__________________________________________________________________________________

J. Zhou, J. Peatross, M.M. Murnane, H.C. Kapteyn,"Enhanced High-Harmonic Generation using 26 Femtosecond Laser Pulses", Physical Review Letters 76, 752 (1996).

S. Backus, J. Peatross, E. Zeek, A. Rundquist, G. Taft, M. Murnane, H. Kapteyn, "16 fs, 1 µJ pulses generated by third-harmonic conversion in air," Optics Letters 21, 665 (1996).

Jianping Zhou, Chung-Po Huang, Margaret M. Murnane, and Henry C. Kapteyn, "Amplification of 26 fs, 2 TW pulses near the gain narrowing limit in Ti:sapphire," Optics Letters 20, 64 (1995).

H.C. Kapteyn and M.M. Murnane, "Femtosecond lasers: the Next Generation," Optics and Photonics News, 5 (3), 20 (1994).

M. M. Murnane, H. C. Kapteyn, M. D. Rosen, and R. W. Falcone, "Ultrafast X-ray Pulses from Laser-Produced Plasmas," Science 251, 531 (1991).

M.T. Asaki, C.P. Huang, D. Garvey, J. Zhou, H.C. Kapteyn, M.M. Murnane, "Generation of 11-fs pulses from a self-mode-locked Ti:sapphire laser," Optics Letters 18, 977 (1993).

G. Taft, A. Rundquist, M. Murnane, H. Kapteyn, K. DeLong, R. Trebino, I. Christov, "Ultrafast optical waveform measurements using Frequency Resolved Optical Gating," Opt. Lett. 20, 743 (1995).

Z. Chang, A. Rundquist, J. Zhou, M. Murnane, H. Kapteyn, X. Liu, B. Shan, J. Niu, M. Gong, X. Zhang, "Demonstration of a Sub-Picosecond X-Ray Streak Camera", to be published in Applied Physics Letters.

H. C. Kapteyn and M. M. Murnane, "Relativistic Pulse Compression," J. Opt. Soc. Am. B 8, 1657 (1991).

S. Backus, J. Peatross, M.M. Murnane, H.C. Kapteyn, "Ti:sapphire Amplifier Producing Millijoule-Level, 21 fs Pulses at 1 kHz", Optics Letters 20, 2000 (1995).

Dr. Rick Trebino and Dr. Ken DeLong, Sandia National Laboratory

Prof. Ivan Christov, Sofia University, Bulgaria

Dr. J.C. Mialocq and Dr. S. Pomeret, French Commissariat a l'Energie Atomique, Saclay, France

Dr. Milan Kokta and Dr. George Venikouas, Union Carbide Crystal Products

Dr. Howard Nathel and Dr. Mordecai Rosen, Lawrence Livermore National Laboratory

Dr. Roy Mead, Aculight Corporation

Dr. Sten Tornigard, Excel/Quantronix

Professor Roger Falcone

Advisees in past 5 years (with Prof. Henry Kapteyn):

Postdoctoral: Dr. Justin Peatross, Dr. Zenghu Chang, Dr. Jaiwen Fan, Dr. Chip Durfee

Ph.D.: Dr. Jianpig Zhou, Dr. Chung-Po Huang, Sterling Backus, Greg Taft, Kendall Read, Andy Rundquist, Erik Zeek, Haiwen Wang, Kira Maginnis, Florian Blonigen

M.S.: Melanie Asaki, Andy Sackreiter, Donna Argento, Chengyu Shi, John McIntosh

Undergraduate: Nicole Dawson, Colette Sackstedter, Alisa Ellingson, Chris Baldwin, Chris Wark, Larry Roy, Marie Tripp

Mr. Nees began his activities in the field of Ultrafast Science as Research assistant in the Masters of Engineering program at the University of Rochester. During the completion of his Master's degree and for three years following, Mr. Nees developed an ultrafast traveling-wave modulator and a laser-diode based electro-optic sampling system. He also refined concepts for improving high-speed electronic sampling measurements.

In 1988 Mr. Nees moved to the University of Michigan where he continued to pursue technologies in ultrafast science. During his time at the University of Michigan he has continued the development of a multi-hundred GHz electronics including optical modulators, detectors, and probes. Most recently, Mr. Nees has headed a project to develop a variable repetition-rate laser with microjoule pulse energy.

Mr. Nees is currently involved in directing the work of four graduate students on the topics of high-speed modulators, high-speed nanoprobes, and compact, high-energy picosecond lasers.

Citizenship: U.S.A.

M.S., Optics The Institute of Optics, University of Rochester, Rochester, New York, 1985.

B.S., Physics Kansas State University, 1983.

Summer Science Institute, Wichita State University, 1978 and 1979.

Assistant Research Scientist, Ultrafast Science Laboratory, University of Michigan, Ann Arbor, Michigan , November 1995 to present.

Senior Associate Research Engineer, Ultrafast Science Laboratory, University of Michigan, Ann Arbor, Michigan , September 1988 - November 1995.

Laboratory Engineer, Laboratory for Laser Energetics, University of Rochester, Rochester, New York, September 1985 - August 1988.

Research Assistant, Laboratory for Laser Energetics, University of Rochester, Rochester, New York, August 1984 - September 1985.

Engineer in Training, United Technologies Research Center, East Hartford, Connecticut, January - August 1984.

S. Sethi, T. Brock, P. K. Bhattacharya, J. Kim, S. Williamson, D. Craig, J. Nees, "High-speed metal-semiconductor-metal photodiodes with Er-doped GaAs," IEEE Electron Device Lett., Vol. 16, No. 3, March, 1995.

J. Kim, S. Williamson, J. Nees, S. Wakana, and John Whitaker, "Photoconductive sampling probe with 2.3 ps temporal resolution and 4-µV sensitivity", Appl. Phys. Lett. 62 (18), 3 May 1993.

T. Motet, J. Nees, S. Williamson, G. Mourou, "1.4 ps Risetime High-Voltage Photoconductive Switching," Appl. Phys. Lettt., 59, 1455-1457, (1991).

J. Nees, G. Mourou, S. Williamson, "100 GHz Traveling-Wave Electro-Optic Phase Modulator," Appl. Phys. Lettt., 54, 1962, (1989).

T. Jackson, J. Nees, R. Vallee, and G. Mourou, "Novel Method for Ultrahigh-Frequency Electro-Optic Time-Domain Reflectometry," Elect. Lett. 23, 1130–1131 (October 1987).

J. Nees and G. Mourou, "Noncontact Electro-Optic Sampling with a GaAs Injection Laser," Electron. Lett. 22, 918–919 (August 1986).

"Electro-Optic Measurement (Network Analysis) System," United States patent #4,745,361, May 17, 1988.

Center for Ultrafast Optical Science phone 313-763-6008

and Dept. Electrical Engineering fax 313-763-4876

University of Michigan e mail (pronko@eecs.umich.edu)

1006 IST Bldg.

2200 Bonisteel Blvd.

Ann Arbor, MI 48109

Ph.D., Physics, University of Alberta (1966)

M.S., Physics, University of Pittsburgh (1962)

B.S., Physics, University of Scranton (Cum Laude - 1960)

Nov. 1992 - present: Associate Director (Industry Liaison), NSF Center for Ultrafast Optical Science; Research Scientist, Dept. Electrical Engineering & Computer Science,

University of Michigan, Ann Arbor, Michigan

1984 - 1992 Director and Chief Scientist- Materials Research Division UES, Inc., Dayton, OH

1982 - 1984 Chief Scientist - Materials Research and Condensed Matter Physics

Universal Energy Systems (UES), Inc., Dayton, OH 45432

1980 - 1982 Senior Physicist; Universal Energy Systems (UES), Inc., Dayton, OH

1972 - 1980 Physicist, Materials Science Division, Argonne National Lab, IL

1968 - 1972 Research Associate, Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada

1967 - 1968 Assistant Professor of Physics, University of Scranton, Scranton, PA

Post Doctoral Fellowship - McMaster University, Institute for Materials Research, 1968-1970.

Presidential Internship at Argonne National Lab - Illinois, 1972-1974.

Sabbatical Year at Solid State Division, Oak Ridge National Lab (1977-1978).

Co-organized Department of Energy Conference on Coatings for Materials

Protection in Energy Systems (Argonne National Lab, 1979).

Symposium Co-organizer for Materials Research Society, Spring 1986 Conference in Anaheim, CA.

Served on organizing committee for the initiation of the MRS Journal of Materials Research.

Chairman of the Full Publications Committee for the Materials Research Society

(MRS, Pittsburgh, PA), 1989-1991.

Member of Long Range Planning Committee for Materials Research Society 1991.

Co-author on four United States patent awards.

Chairman of organizing committee for IEEE/LEOS Summer Topical Conference 1996

on "Advanced Applications of Lasers in Materials and Processing".

Listed in Who's Who in American Midwest, American Men and Women of Science, Bohmiche Physicaliche Gesellshaft

American Physical Society (APS), Materials Research Society (MRS),

Institute of Electrical and Electronic Engineers (IEEE).

5 RELEVANT PUBLICATIONS:

P.P. Pronko, S.K. Dutta, J. Squier, J.V. Rudd, D. Du, and G. Mourou, "Machining of Sub-Micron Holes using Femtosecond Laser at 800 nm" Optics Comm. 114, 106 (1995).

F. Qian, R.K. Singh, S.K. Dutta, P.P. Pronko, "Laser Deposition of Diamond-Like Carbon Flms at High Intensities," Appl. Phys. Lett, 67 3120 (1995).

P.P. Pronko, S.K. Dutta, D. Du, and R. Singh, "Thermophysical Effects in Laser Processing of Materials with Picosecond and Femtosecond Pulses" Journal of Applied Physics 78 6233 (1995)

P.P. Pronko, P.A. VanRompay, R.K. Singh, F. Qian, D. Du, and X. Liu, "Laser Induced Avalanche Ionization and Electron-Lattice Heating of Silicon with Intense Near IR Femtosecond Pulses" Materials Research Society, Symposium Proceedings Series Vol. 397, pp. 45-52 (1996)

P.A. VanRompay, X. Liu, R.K. Singh, and P.P. Pronko, "Surface Related Phase Changes and Structure Modification in Semiconductors with Ultrafast Laser Pulses" Proceedings of IEEE/LEOS Summer Topical Conference on Advanced Applications of Lasers in Materials and Processing, Keystone, CO. August 1996.

F. Qian, R.K. Singh, S. Dutta, P.P. Pronko, and W.H. Weber,"Femtosecond Laser Deposition of Diamond-Like Carbon Films" Proc. Materials Research Society, Symposium Proceedings Series Vol. 397 (1996)

P.P. Pronko, G. Mourou, P.A. VanRompay, X. Liu, D. Du, R.K. Singh and F. Qian,"Electron-Lattice Heating from Avalanche Ionization in Silicon with Near Infra-Red Ultrafast Laser Pulses" Optical Society of America, Ultrafast Phenomena Conference, San Diego, May 1996.

P.G. Snyder, M.C. Rost, G.H. Bu-Abbud,Jae Oh, J. Woollam, D. Poker, D.E. Aspnes, D. Ingram, and P.P. Pronko,"Study of Mo, Au, and Ni-Implanted Molybdenum Laser Mirrors by Multiple Angle of Incidence Spectroscopic Ellipsometry" J. Appl.Phys. 60 779 (1986).

S.R. Wilson, W.M. Paulson, R.B. Gregory, G. Tam, C.W. White, B.R. Appleton, A.K.Rai,and P.P. Pronko,"Thermal Stability of Electrically Active Dopants in Laser Annealed Silicon Films" J. Appl. Phys 54, 5004 (1983).

J.C. Wang, R.F. Wood, and P.P. Pronko,"Dopant Profile Changes Induced by Laser Irradiation of Silicon: Comparison of Theory and Experiment," J Appl. Phys. Lett. 33 455 (1978).

GRADUATE STUDENTS:

Fan Qian (Thesis defense June 20, 1996)

Graduate - Joseph Lipson, Roy Krause

Post Doctoral - Roger Kelly, John Davies

BIOGRAPHICAL SUMMARY

Principal Investigator: STEPHEN C. RAND

Professional Experience:

1978-1980 World Trade Postdoctoral Fellow - IBM Research Laboratory, San Jose, CA

1980-1982 Research Associate - Varian Laboratory, Dept. of Physics, Stanford University 1982-1987 Member of Technical Staff - Hughes Research Laboratory, Malibu, CA

1987-present Associate Professor - Division of Applied Physics, Depts. of Physics, Electrical Engineering and Computer Science, University of Michigan

Education:

M.Sc. (Physics) - 1974, University of Toronto, Toronto, Ontario

Ph.D. (Physics) - 1978, University of Toronto, Toronto, Ontario

Awards: University of Toronto: Blythe scholar (1972, 1977); U. of T. Open Fellowship (1975); Ontario Graduate Fellowship (1973); Burton Fellowship (1974)

World Trade Postdoctoral Fellowship (1978-80)

9 Hughes Research Invention Awards (1983-85)

7 Patent Awards (solid state lasers and fiber-optic devices)

Honors: 1989 - CNRS Invited Professor - University of Grenoble

1994 - Fulbright Scholar - Ecole Normale Superieure (College de France, Paris)

Topical Editor - Journal of the Optical Society B

Research Interests:

Nonlinear laser spectroscopy in atomic vapors, widegap semiconductors, upconversion materials and development of upconversion lasers for the generation of short wavelength radiation. Also, fundamental studies of nonlinear dynamics in these systems.

Mailing Address:

Dept. of EECS, 1301 Beal St., University of Michigan, Ann Arbor, MI 48109-2122

1. D. Redman, S. Brown, R. Sands and S. C. Rand, "Spin Dynamics and Electronic Structure of N-V Centers in Diamond," Phys. Rev. Lett. 67, 3420 (1991).

2. P. Xie and S. C. Rand, "Cw mode-locked visible upconversion laser," Opt. Lett. 17, 1116 (1992).

3. D. Redman, S. Brown and S. C. Rand, "Origin of Persistent Spectral Hole-burning of N-V Centers in Diamond," JOSA B9, 768 (1992).

4. H. Ni and S. C. Rand, "Avalanche Phase Conjugation," Opt. Lett. 17, 1222 (1992).

5. P. Xie and S. C. Rand, "Four-fold Upconversion Laser," Appl. Phys. Lett. 63, 3125 (1993).

6. M. Hehlen, H. Gudel, J. Rai, S. Rai and S. C. Rand, "Cooperative Bistability in Dense, Excited Atomic Systems," Phys. Rev. Lett. 73, 1103 (1994).

7. P. Xie and S. C. Rand, "Cooperative Nonlinear Dynamics," JOSA B11, 901 (1994).

8. A. Lenef, D. Kreysar and S. C. Rand, "Laser-induced Collisional Avalanche in Atomic Cesium," Phys. Rev. A51, 1731 (1995).

9. A. Lenef and S. C. Rand, "Electronic Structure of the N-V Center in Diamond: Theory and Experiments," Phys. Rev. B15, April 15 (1996).

There are no collaborators other than those already cited in the publication list.

C. Recent Collaborators:

None other than co-authors above.

D. Graduate and Postdoctoral Advisors:

Herbert L. Strauss, University of California, Berkeley

Bruce S. Hudson, University of Oregon

Robin M. Hochstrasser, University of Pennsylvania

E. Graduate and Postdoctoral Advisees:

Only current students

University of Michigan: 1976-77, instructor and postdoctoral research fellow.

University of Rochester Laboratory for Laser Energetics and the Exxon Research and Engineering Company: 1977-78, Physicist.

Hughes Research Laboratories: 1982-85, Senior Member of the Technical Staff (Physicist); 1975-82, Member of the Technical Staff.

University of Michigan: 1989-current, Professor of Electrical Engineering and Physics; 1990-current, Research Scientist for Institute of Gerontology, School of Medicine; 1985-1989, Assoc. Professor of Electrical Engineering and Physics; 1985-1990, Associate Research Scientist, Institute of Gerontology, School of Medicine. Area Chairman for Optics, EECS Dept.; 1990-. Director, Optical Science Laboratory, EECS Dept.; 1988-.

1975 - M.S. in Nuclear Science, University of Michigan

1973 - M.S. in Electrical Science, University of Michigan

1972 - A.B. in Physics, University of North Carolina at Chapel Hill

Honors and Awards:

Member, Phi Beta Kappa and Sigma Xi

Horace H. Rackham Doctoral Fellow, 1974

Hughes Research Laboratory Doctoral Fellow, 1975

National Science Foundation Postdoctoral Fellow, 1976

National Institute of Health Senior Investigator Fellowship, 1988-1990

Research Excellence Award, 1991 - Univ. of Michigan College of Engineering Distinguished Panel Member, AFOSR, 1991

OSA Fellow, 1992

American Physical Society Fellow, 1994

Who's Who in America, 1996

Dr. Joseph Mersol

Dr. Stephen Cundiff

Dr. Min Jiang

Dr. Michael Freeman

Dr. Daniel Kilper

Dr. Vinod Subramaniam

Dr. Kyle Ferrio

Dr. James Kim

Dr. John Erland

Graduate students - 7; Post-doc fellows - 2

Professor David Bach

Born: December 19, 1946

Citizen of USA

Referee for: Phys. Rev. B

Phys. Rev. Letters

Solid State Communications

Applied Physics Letters

J. of Physics and Chemical of Solids

Reviewer for NSF, DoD, and DoE

Elect. Eng. and Comp. Sci. Dept.

1006 IST Bldg.

University of Michigan, Ann Arbor, MI 48109-2099

University of California, Los Angeles, Physics, B.S. (1981), M.S. (1983), Ph.D., (1987).

Thesis: Nonlinear Behavior of Electron Plasma Waves Driven by Stimulated Raman Backscattering

Postdoctoral Fellow, AT &T Bell Laboratories and Univ. of Maryland (9/87-9/89)

Assistant Research Scientist, Elect. Eng. and Comp. Sci. Dept., University of Michigan (9/89-9/95)

Adjunct Professor, Nuclear Engineering Dept., University of Michigan (9/94)

Associate Research Scientist, Elect. Engin. and Comp. Sci. Dept., University of Michigan (9/95)

D. Umstadter, S.-Y. Chen, A. Maksimchuk, G. Mourou, and R. Wagner, "Nonlinear Optics in Relativistic Plasmas and Laser Wakefield Acceleration of Electrons," Science (accepted for publication, 1996).

D. Umstadter, J.-K. Kim, and E. Dodd, "Laser Injection of Ultrashort Electron Pulses into Wakefield Plasma Waves," Phys. Rev. Lett 76, 2073 (1996).

D. Umstadter, E. Esarey, and J.-K. Kim, "Nonlinear Plasma Waves Resonantly Driven by Optimized Laser Pulse Trains," Phys. Rev. Lett. 72, 1224 (1994).

D. Umstadter, J.-K. Kim, E. Esarey, E. Dodd and T. Neubert, "Resonant Laser-Driven Plasma Waves for Electron Acceleration," Phys. Rev. E 51, 3484 (1995).

J. Workman, A. Maksimchuk, X. Liu, U. Ellenberger, J.S. Coe, C.-Y. Chien and D. Umstadter, "Control of Bright Picosecond X-Ray Emission from Intense Sub-Picosecond Laser-Plasma Interactions," Phys. Rev. Lett. 75, 2324 (1995).

Five Other Related Publications (39 total)

X. Liu, R. Wagner, A. Maksimchuk, E. Goodman, J. Workman, D. Umstadter and A. Migus, "Nonlinear Temporal Diffraction and Frequency Shifts Resulting from Pulse Shaping in Chirped-Pulse Amplification Systems," Opt. Lett. 20, 1163 (1995).

X. Liu and D. Umstadter, "Self-Focusing of Intense Subpicosecond Laser Pulses in a Low Pressure Gas," OSA Proceedings on Shortwave-length V, 1993, P.B. Corkum and M.D. Perry, eds., (Optical Society of America, Washington, D.C., 1993), 17, p. 45.

X. Liu, D. Umstadter, E. Esarey and A. Ting, "Harmonic Generation by an Intense Laser Pulse in Neutral and Ionized Gases," IEEE Trans. Plasma Sci. 21, 90 (1993).

X. Liu and D. Umstadter, "Competition Between Ponderomotive and Thermal Pressures in Short-Scale-Length Laser-Plasmas," Phys. Rev. Lett. 69, 1935 (1992).

L.-H. Yu, E. Johnson, D. Li, and D. Umstadter, "Femtosecond Free-Electron Laser by Chirped Pulse Amplification," Phys. Rev. E 49, 4480 (1994).

Recent Collaborators

Lawrence Jones

Gérard Mourou

Margaret Murnane

Henry Kapteyn

Michael Downer

Robin Marjoribanks

Eric Esarey

Torsten Neubert

John Apruseze

Eric Johnson

L.-H. Yu

Xinbing Liu (grad and postdoc)

Marc Nantel (postdoc)

Jonathan Workman (grad)

Joon Koo Kim (grad)

Evan Dodd (grad)

Robert Wagner (grad)

Szu-Yuan Chen (grad)

John Dawson and Chan Joshi (grad)

Richard Freeman and Thomas McIlrath (postdoctoral)

A. Vitae

Address: Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel,

Ann Arbor, Michigan 48109-2099

Education: Ph.D., University of Rochester (Electrical Engineering); M.S., University of Rochester (Electrical Engineering); Sc. B., Bucknell University (Physics)

Current, Associate Research Scientist, Department of Electrical Engineering and Computer Science, University of Michigan

1995, Visiting Professor, First Class (University), University of Savoie, France

1989-1994, Assistant Research Scientist, Department of Electrical Engineering and Computer Science, University of Michigan

1988, Postdoctoral Fellow, University of Rochester, Laboratory for Laser Energetics

1996, The Microwave Prize of the IEEE Microwave Theory and Techniques Society

1996, The 1995-96 Research Excellence Award of the Department of Electrical Engineering and Computer Science, University of Michigan

1990, NASA Certificate of Recognition presented "For the creative development of a technical innovation."

B. Publications (Related to the proposal)

H. Cheng, J.F. Whitaker, T.M. Weller, and L.P.B. Katehi, "Terahertz-bandwidth characteristics of coplanar transmission lines on low permittivity substrates," IEEE Trans. Microwave Theory Tech., vol. 42, pp. 2399-2406 (Dec. 1994).

H. Cheng, J.F. Whitaker, T.M. Weller, and L.P.B. Katehi, "Terahertz-bandwidth pulse propagation on a coplanar stripline fabricated on a thin membrane," IEEE Microwave and Guided Wave Lett, vol. 4, pp. 89-91, (Mar. 1994).

J.-R. Hwang, H.-J. Cheng, J.F. Whitaker, and J.V. Rudd, "Photoconductive sampling with an integrated source follower/amplifier," Applied Physics Lett., vol. 68, pp. 1464-1466 (1996).

J.F. Whitaker, "Optoelectronic applications of LTMBE III-V materials," Mat. Sci. Eng., vol. B22, pp. 61-67 (1993).

Other significant publications:

J.-R. Hwang, R.K. Lai, J. Nees, T.B. Norris, and J.F. Whitaker, "A field-sensitive photoconductive probe for sampling through passivation layers," submitted to Appl. Phys. Lett., June 1996.

J.F. Whitaker, "Opto-switches using low-temperature MBE GaAs," to be published as an invited book chapter for Properties of Gallium Arsenide, 3rd Edition, M. Brozel and G. Stillman, Eds.

J.F. Whitaker, H.H. Wang, C.Y. Sung, T. Sosnowski, T.B. Norris, H. Fujioka, and Z. Liliental-Weber, "Ultrafast carrier response of low-temperature-grown and arsenic-implanted GaAs," Lithuanian J. of Physics, vol. 35, pp. 594-600 (1995).

J.F. Whitaker, F. Gao, and Y. Liu, "Terahertz-bandwidth pulses for coherent time-domain spectroscopy," in Nonlinear Optics for High-Speed Electronics and Optical Frequency Conversion, N. Peygambarian, H. Everitt, R.C. Eckardt, D.D. Lowenthal, Eds., Proc. SPIE, vol. 2145, pp. 168-177 (1994).

C.Collaborators

Steve Williamson, Dr. Janis Valdmanis, Dr. Zuzanna Liliental-Weber, Dr. Wladek Walukiewicz, Prof. Eicke Weber, Prof. Anatoly Frenkel, Dr. Julia Phillips, Prof. David Look, Dr. Donald Harter, Dr. Martin Fermann, Dr. Greg Sucha, Prof. Michael Melloch, Prof. Arthur Gossard, Prof. Umesh Mishra, Dr. Frank Smith, Dr. Douglas Dykaar, Marcel Bouvier, Dr. Daniel Kaplan, Prof. Jean-Louis Coutaz, Prof. Todd Weatherford

D. Students

Joo-Hiuk Son, Heng-Ju Cheng, Hsi-Hui Wang, Yongqian Liu (total students advised is also 4)

Post-docs: Feng Gao and Paul Grenier (current); total post-doc sponsorship is 2

E. Advisors

Graduate and post-doctoral advisors are Profs. Thomas Y. Hsiang and Gerard Mourou

Associate Professor

Department of Electrical Engineering and Computer Science

University of Michigan

Ann Arbor, MI 48109

Integrated Optics, Lasers, Nonlinear Optics, and Optical Communications

Ph.D. Electrical Engineering, University of Michigan, 1981.

M.S. Electrical Engineering, University of Michigan, 1977.

B.S. Electrical Engineering, Pennsylvania State University, 1976.

University of Michigan, Associate Professor, 1994-present.

University of Michigan, Assistant Professor, 1988-1994.

Massachusetts Institute of Technology Lincoln Laboratory

Satellite Communication System Group, 1984-1988.

Optical Communications Technology Group, 1984-1988.

Environmental Research Institute of Michigan

Research Assistant (part-time), 1978-1981.

Professor Winick's earliest work involved the design of optimumholographic elements. This work, completed while he was a student at the University of Michigan, led to two extensively referenced papers which represent one of the first treatments of this subject.

In 1981, he completed his Ph.D. work and joined the Massachusetts Institute of Technology Lincoln Laboratory. At MIT he was involved with millimeter wave and optical communication system design. As a member of the technical staff, he developed algorithms for acquisition and tracking, performed atmospheric turbulence studies and measurements, and did experimental studies on the spatial mode matching efficiencies of AlGaAs semiconductor lasers for heterodyne communication.

In 1988, he joined the faculty of the Electrical Engineering andComputer Science Department at the University of Michigan as an Assistant Professor and established an experimental program in glass and crystal integrated optics. In 1994 he was promoted to an Associate Professor with tenure. His work has focussed primarily on glass/crystal integrated optics and information theory for optical channels. His most recent research has led to the demonstration of an integrated distributed Bragg reflector laser in a rare earth-doped glass waveguide, an optical direct-write technique for grating fabrication in ion- exchanged glass waveguides, a chirped grating, integrated optical circuit for dispersion compensation, and an erbium:ytterbium co-doped glass waveguide laser.

G.L. Vossler, C.J. Brooks and K.A. Winick, "Modeling and Characterization of Erbium:Ytterbium Glass Waveguide Lasers," paper CFJ6, Conference on Lasers and Electro-Optics, Anaheim, CA, Jun. 2-7 (1996).

G.L. Vossler, C.J. Brooks and K.A. Winick, "Chromium Indiffused LiNbO3

Waveguide Amplifier," paper CFJ5, Conference on Lasers and Electro-Optics,

Anaheim, CA, Jun. 2-7 (1996).

C.J. Brooks, G.L. Vossler and K.A. Winick, "Integrated Optic Dispersion Compensator Using Chirped Gratings, Optics Lett., 20 368-370, (1995).

C.J. Brooks, G.L. Vossler and K.A. Winick, "Phase Response Measurement Technique for Waveguide Grating Filters," Appl. Phys. Lett., 66, 2168-2170, Apr. (1995).

J.E. Roman and K.A. Winick, "Photowritten Gratings in Ion-Exchanged glass Waveguides," Optics Lett., 18, 808-810, May (1993).

J.E. Roman and K.A. Winick, "Waveguide Grating Filters for Dispersion Compensation and Pulse Compression," IEEE J. Quantum Electron., 29, 975-982, Mar. (1993).

J.E. Roman and K.A. Winick, "Neodymium-doped Glass Channel Waveguide Laser Containing an Integrated Bragg Reflector," Appl. Phys. Lett., 61, 2744-2746, Dec. (1992).

K.A. Winick, "Effective-Index Method and Coupled-Mode theory for Almost-Periodic Waveguide Gratings: A Comparison," Appl. Optics., 31, 757-764, Feb. (1992).

K.A. Winick, "Design of Grating-Assisted Waveguide Couplers With Weighted Coupling," IEEE J. Lightwave Technol., 9, 1481-1492, Nov. (1991).

K. A. Winick and J.E. Roman, "Design of Corrugated Waveguide Filters by Fourier-Transform Techniques," IEEE J. Quantum Electron., 26, 1918-1929, Nov. (1990).

* Most Significant

Bernard Couillaud, Chief Operating Officer, Coherent, Inc., Santa Clara, CA