Date Prepared: 10/1/99

This past year, CUOS had a robust scientific and technological productivity that continued to enlarge our array of interdisciplinary activities, ranging from terahertz electronics to nuclear physics to astrophysics. Expressed in electron volts, that is, photon energy in the visible regime, CUOS activities both in science and technology range from the milli-electron-volt to the giga-electron-volt—12 orders of magnitude!

The science and technology at the center are well balanced and tightly woven. CUOS continues to be an important innovator in the field. This is the case, for example, with femtosecond micromachining and precision surgery. First demonstrated at CUOS, they are becoming the most important real-world applications of femtosecond lasers. This technique is being extended to the biochip, for drug discovery and DNA sorting. Other examples are isotope separation and femtosecond epitaxy laser deposition. They illustrate the CUOS aptitude to innovate, promote, and integrate new programs in the impressive scientific, engineering, and life science CUOS fabric.

Let’s review some of the highlights. Starting with ultrahigh intensities, CUOS observed the relativistic character of the laser free electron interaction at intensities greater than 1018 W/cm2 This effect is also known as nonlinear Thomson scattering.

At somewhat lower intensities, ~1016 W/cm2, the generation of the laser harmonics, up to the 300th order, well in the water window, was confirmed. The pulse duration was measured to be 11 fs.

Using Thz single cycle technology, our Thz group, directly visualized the Gouy shift happening when an electromagnetic wave is going through a focus. The ultrafast science group has made important contributions, in the area of coherent control in semiconductor quantum structures, coherent phonon and understanding of the dynamics of molecular system.

In the medical area, CUOS researchers, in collaboration with the University of Michigan’s Kellogg Eye Center, have begun clinical trial experiments on human patients in Budapest, Hungary, and Rome, Italy. The same group has demonstrated that femtosecond lasers could be used in cataract surgery to trigger the breakdown of the lens by an ultrasound beam. Experiments on glaucoma are actively being pursued by studying the propagation of infrared pulses through the sclera.

The study of laser ablation and ion energy distribution convinced us of the potential offered by femtosecond pulses for thin-film growth. The advantages over conventional laser deposition include (1) a fully ionized plume, in contrast to long-pulse deposition, which produces incomplete ionization with a large amount of neutrals and particulates. The films obtained from femtosecond ablation are remarkably clean. (2) The laser can produce intensities always higher than the ionization intensities of any materials. Therefore, with femtosecond lasers any materials can be ablated in a controlled way and deposited on any substrate. We have shown recently the deposition of epitaxial BN and SnO₂ semiconductor using a femtosecond laser. In the process of thin-film growth, a new isotope separation technique was discovered due to the presence of strong magnetic and electric fields produced in the plasma.

CUOS has been an important player in the marriage of CPA (Chirped Pulse Amplification) lasers with synchrotrons. The work done on streak cameras and high-voltage switching made possible the operation of the streak camera in jitter-free and accumulation mode. Using the long x-ray pulse for probe in conjunction with the streak camera, a subpicosecond time-resolved system has been demonstrated at the European Synchrontron Radiation Facility in collaboration with the INRS (Canada) and the Advanced Light Source (ALS). A time-resolved structural probe in the picosecond timescale has been demonstrated at ALS. (See below).

Two major hurdles need to be overcome in light-matter interaction in the ultrahigh-intensity regime. The first is the production of a diffraction-limited spot with large-aperture parabolas. The second is the generation of ultrahigh intensities with ultrahigh contrast. CUOS has been a pioneer in the application of deformable mirrors. It has demonstrated that deformable mirrors could correct large numerical apertures parabolas to function better than much more expensive ones. A typical CPA system with focusing optics produces a spot size with only 20–30 % of the energy in the main lobe. Adaptive optics makes it possible to reach 80–90%—a gain of 3–4 in intensity (see Picture 8). Improving the laser focusing as opposed to increasing the laser energy by a factor three-to-four is the most economical way to increase the intensities. Contrast improvement was obtained by frequency-doubling the laser beam. The aberrations introduced by the intensity-dependent index of refraction were measured and corrected, once again using the deformable mirror. As an example of center activities, the deformable mirror technology developed for high-intensity lasers has been transferred to our microscopy group at CUOS. It is used now to perform confocal microscopy for the first time by rastering the beam and keeping the sample fixed. The advantages are (1) it makes possible the study of biological samples that cannot move and (2) the spherical aberrations introduced by the sample thickness can be removed. These are a few examples showing the interconnections among the various efforts at the Center.

The center maintains a strong relationship with other domestic and foreign institutions. With the Advanced Light Source, we conducted joint research on the implementation of a jitter-free streak camera on the synchrotron. We were able to time resolve for the first time a laser-induced phase transition on the picosecond time scale with a synchrotron light source. Similar work is taking place at the European Synchrotron Facility. The INRS au Quebec has been an important player in the development of streak cameras. With Old Dominion University, we have developed a picosecond, time-resolved, electron diffraction system to time resolve phase transition in bulk and surface of crystals. With Hampton University, work on a Laser Wakefield Accelerator is being jointly conducted; a postdoctoral fellow is shared, and instrumentation is designed at CEBAF and implemented at CUOS.

The Fellows Program, contributes to bring outstanding researcher to CUOS. Details are given later in this annual report. In addition, the Fellows Program has resumed its schedule of workshops, with a successful meeting on Super-Intense Laser-Atom Physics held at American University in May, following CLEO. It also helps to maintain our weekly seminar series by bringing top outside speakers. Coupled to the Fellow program, on the international scene, a joint program addressing the fundamental issues involved in ultraintense lasers has been implemented between the ENSTA/Ecole Polytechnique and CUOS. Postdoctoral researchers are exchanged.

The dominant technology transfer process operative at CUOS has been the licensing of new patented technology and the spin-off of new companies that carry center technology to the marketplace. It is anticipated that this mode of operation will continue. All of our spin-off companies are undergoing rapid growth in technology development, sales volume, and number of employees. Three such companies are now in operation and doing very well as start-ups. These are Clark/MXR, Picometrix, and IntraLase. They are all based on applications of femtosecond laser technology.

Patents from our center that were implemented through the UM Technology Management Office (TMO) as of last year: 42 Patent Disclosures to the UM TMO; Patent Applications to the US Patent Office, 15 Patents Granted by the Patent Office, 10 Licenses Sold to Industry. Four new patents are under development as a result of research over the past year.

K-12 Education Outreach at CUOS continues, through our sponsored Reach Out! student group, to place hundreds of volunteers at dozens of sites in Ann Arbor, Ypsilanti, and Pontiac in science clubs, mentoring programs, and combinations of the two. New programs this year included limited collaborations with four new partner groups, formal career exploration programs for children and teens, a summer day camp for disadvantaged local children, and our first Research Experiences for Teachers (RET) program in the summer. Plans for next year are to refine our RET program, to begin new volunteer placements at the six public housing sites in Ann Arbor, to expand our career club collaboration with Ann Arbor Kiwanis, and to complete the transformation of all our programs into true mentoring, with continuing relationships and a broader scope of assistance to young people.

Faculty: Prof. Phillip Bucksbaum, Dr. Zenghu Chang, Ph.D. , Prof. Henry Kapteyn. Ph.D. , Prof. Gérard Mourou, Ph.D., Prof. Margaret Murnane, Ph.D., John Nees, Assistant Research Scientist.

Collaborators: Prof. Roger Falcone, UC Berkeley; Dr. Phillip Heimann, Lawrence Berkeley Lab.

Students; Subrat Biswal, Hsiao-Hua Liu.

a. High-saturation-fluence laser materials - Amplification with high-saturation-fluence materials For applications in medicine and industry stability and compactness, which can be afforded only by diode-pumped systems, are needed to make new technologies developed at CUOS viable in the marketplace. We have concentrated study on high-saturation-fluence materials for these applications because the fundamental relation between emission lifetime and saturation fluence indicates that higher energy will be obtained from such materials using available diode pump lasers. From our study we learned that a low-loss, low-gain regenerative amplification is the best way to take extract energy from such materials.

This year we demonstrated a 1-mJ directly diode-pump Yb:glass laser with a pulse duration of 200 fs and a pulse repetition rate of 150 Hz. This system employs a new gain design with multiple total internal reflections and Brewster transmission to achieve good cooling and pump coupling with very low signal loss. Using a flashlamp-pumped Ti:sapphire pump laser to simulate laser diode pumping we have also presented amplification to 15 mJ at 10 Hz repetition rate and 150 mJ at 1 Hz. Ytterbium-baser laser materials ultimately offer the best potential for a diode-pumped high-repetition-rate Petawatt laser.

b. Ultrafast detectors - CUOS recognized a few years ago the importance of pursuing not only the development of fast laser sources alone but also the implementation of fast detectors, in the x-ray and visible regimes. CUOS has supported the research on jitter-free streak camera has a mean to simultaneously increase their sensitivity and temporal resolution. We have demonstrated the concept on the Advanced Light Source, and the European Synchrotron Radiation Facility with INRS (Institut National de la Recherche Scientifique) where subpicosecond jitter has been demonstrated. It has been used to perform time-resolved x-ray diffraction studies in the picosecond time scale. This work has been extended to the visible at CUOS for studies on photosynthesis and photochemistry

c. Time-resolved X-ray Diffraction with a Streak Camera - The first ultrafast X-ray experiment we have worked on is time-resolved X-ray diffraction, which is a newly emerged technology to directly probe the structural dynamics of matter. We have developed a laser triggered streak camera for the diffraction experiments on synchrotrons. In collaboration with Prof. Roger Falcone at UC Berkeley and Dr. Phillip Heimann at Lawrence Berkeley Lab, we have employed time-resolved X-ray diffraction with picosecond temporal resolution to observe scattering from impulsive-generated coherent acoustic photons in femtosecond laser-excited InSb crystal. At low laser fluences, we observed phonon frequencies up to 0.1 THz. For sufficiently high-laser fluences, we found a reversible, optical-induced phase transition that develops on a time scale equal to one-half a phonon period. The application of these results will allow precise control of the temporal evolution of the x-ray diffraction efficiency, leading to new, potentially useful, devices such as ultrafast X-ray switch.

During the next year we will support the development of a multi-hundred-terawatt laser system using Ti:sapphire technology. This system will deliver 7 J in 30 fs for experiments in relativistic plasma physics. We will build a kilohertz-repetition-rate Ti:sapphire laser capable of delivering 20-fs pulses at an energy of 5 mJ. This laser will make use of a cryogenically cooled Ti:sapphire crystal. The study of high-saturation-fluence materials will extend to diode-pumpable crystals for 1-mJ and 100-mJ sources. Further exploration of the diode-pumped milijoule regenerative amplifier will include testing in an end-pumped configuration to avoid the most critical thermal distortions.

The current time resolution of our X-ray diffraction work at ALS is about 2 ps, limited by the jitter of the photoconductive switch used to trigger the streak camera. During next year, we will improve the design of the switch and trigger the switch with more stable lasers. We expect to achieve ~500 fs resolution, which will push the X-ray diffraction to a new stage. We plan to collaborate with scientist at Argonne National Lab to do the time-resolved X-ray diffraction with the 3^rd generation synchrotron: Advanced Light Source.

Faculty: Dr. Sterling Backus, Ph.D., Prof. Phil Bucksbaum, Ph.D., Dr. Zenghu Chang, Ph.D., Prof. Roy Clarke, Ph.D., Dr. Anatoly Maksimchuk, Ph.D., Prof. Margaret Murnane, Ph.D., Prof. Henry Kapteyn, Ph.D., Prof. Gerard Mourou. Ph.D., John A. Nees, Assistant Research Scientist, Prof. Xiaoqing Pan, Ph.D., Dr. Peter P. Pronko, Ph.D., Prof. Donald Umstadter, Ph.D.

Research Fellow: Dr. Charles Durfee, Ph.D.

Students: Szu-yuan Chen, Evan Dodd, Kirk Flippo, Paul Han, Youngsik Kim, Mohan Krishnan, Ned Saleh, Chris Stewart, Paul VanRompay, Haiwen Wang, Xiaofang Wang, Fritz Weihe, Zhiyu Zhang.

a. Interactions with plasmas

Relativistic nonlinear Thomson scattering - We have successfully measured for the first time the incoherent relativistic Thomson scattering of an intense laser from previously stationary electrons in plasma, an effect predicted by Landau and Lifshitz almost sixty years ago. The unique angular patterns of the second and third harmonics were detected, revealing the figure-eight motion of the electron under an intense linearly polarized laser field. As evidence of the fundamental significance of the result, it was chosen as the cover story in the journal Nature [57]. More recently, we have extended these results with a measurement of coherent relativistic Thomson scattering. The third harmonic was emitted in a forward cone, the angle of which was found to be consistent with the Bragg condition.

Electron Acceleration in Relativistic Plasma Waves - New intriguing results on electron acceleration in a self-modulated laser wakefield have been obtained. Test-particle simulations have been performed to explain the experimental observations. The results have been accepted for publication in Physics of Plasmas [61]. Furthermore, the study of the excitation and damping of a self-modulated laser wakefield has been completed. Spatially, temporally and angularly resolved collective Thomson scattering was used to reveal the growth and decay of the electron plasma waves and ion acoustic waves. The results indicate that both electron beam loading and modulational instability play important roles in damping of an electron plasma wave in our experiment. In collaboration with Cynthia Keppel, Warren Buck and Paul Gueye from Hampton University, we are in the process of building an electron beamline for the application of ultrashort electron pulses to nuclear physics experiments.

High-energy ion acceleration in ponderomotively driven plasma channels A number of proposed applications of ultra-high intensity short laser pulses require laser guiding for distances much longer than a Raleigh length without considerable energy loss and significant diffraction. Using an interferometric technique we studied the dynamics of interaction of the relativistically intense laser pulse with a He gas jet [59]. We observed a stable plasma channel with the on-axis electron density approximately 10 times less than its maximum value. A high radial velocity of the surrounding gas ionization has been observed after the channel formation and it was attributed to the fast ions expelled from the laser channel and propagating radially outwards. We developed a kinetic model, which describes the plasma channel formation and a subsequent ambient gas excitation and ionization. We showed for the first time that intensity of relativistically self-focused laser beam could be 3 times higher than the vacuum intensity. The estimated maximum energy of accelerated ions is about 500 keV and the total energy of fast ions is 5% of the laser pulse energy. This work demonstrates one more application of ultra-high intensity short laser pulses, a ``table-top ion accelerator'' that can be used for nuclear physics research on a short time scale.

X-ray radiation from extremely Stark broadened ions in dense plasmas We applied high spectral resolution x-ray spectroscopy to study the high-density effects on the emission of the multiply charged ions [18,60,62]. We observed the effects of the extreme high density in a subpicosecond laser produced plasma. Detailed theoretical analysis, which includes the dielectronic satellites emission and Stark broadening, showed that both spectra at high-contrast illumination could be fitted with the electron density that is 70-95% of the solid-density magnesium. To our knowledge this is the highest inferred electron density of hot plasma produced by a high-intensity ultrashort laser pulse. These results suggest that the radiative pressure plays an important role in interaction of relativistic intensities clean laser pulses with plasma, altering the plasma expansion and even compressing solid-density plasma.

b. Interactions with Atoms and Molecules

We used high harmonics to perform new kinds of investigations of atoms and molecules. This year we concluded our studies of core-level absorption in molecular iodine, which has a sharp resonance near the 29th harmonic of the Ti:sapphire laser. We have observed this absorption, and furthermore we have seen some evidence for dependence of the absorption on the state of the molecule: Pump-probe experiments where the absorption follows excitation of the iodine molecule by a 500 nm ultrafast pulse yield an ionization signal that depends on the presence of both the visible and vuv pulses. Frederick Weihe performed these experiments in collaboration with the Kapteyn-Murnane group. Beyond this, however, there are a number of significant challenges to overcome before high harmonics become a spectroscopic tool. For example, we do not yet have a good way of selecting an individual harmonic while still retaining short pulse duration.

c. Materials Research

Isotope Enrichment and Separation in Ultrafast Laser Ablation Plumes We have discovered a highly efficient isotope enrichment and separation process that is directly associated with ultrafast laser ablation plumes formed at solid surfaces. The effect has been confirmed in a range of elemental materials including B, Cu, Ti, Zn, and Ga. A paper has been published in Physical Review Letters describing this phenomenon and explaining its occurrence through the interaction of energetic ions in the ablation plume with plasma generated magnetic fields. The process can be modeled as a self-generated plasma centrifuge that provides factors of two or more enrichment in isotopic composition of deposited films on collector substrates. This phenomenon suggests itself as a valuable scientific method for measuring internal electromagnetic fields and other fundamental properties of laser ablation plasmas. In addition, it is a simple and direct means for isotope separation and, from a practical standpoint, provides a method for the direct deposition of engineered isotopically enriched thin films.

Thin Film Deposition by Ultrafast Laser Ablation into Activated Gas Discharges - An area of continuing study has been the process of forming high temperature nitride materials in thin-film form using femtosecond pulsed laser deposition. The ablation plumes from ultrafast lasers have certain unique properties, some of which are of potential value in fabricating thin films of high temperature nitrides such as TiN and BN. We have demonstrated the ability to form epitaxial layers of TiN on silicon using the method of domain epitaxy with ultrafast laser ablation in a nitrogen gas discharge. This same process has been under study for depositing epitaxial cubic phase BN. The later material is valuable in its cubic form for use as a wide band-gap semiconductor and as a hard industrial coating. Other methods have been developed to fabricate the polycrystalline cubic phase of BN, however it is particularly difficult to synthesize the single crystal cubic phase in an engineered and useful form. We have some preliminary results suggesting that a domain-epitaxy process on TiN could form it. This is particularly intriguing since TiN itself represents an important source of hard coating material for industrial applications. Being able to combine these two materials in a superlattice represents a substantial opportunity for mechanical and electrical engineering applications. The nature of energetic ions in ultrafast laser ablation plumes represents an important source of deposition flux for the above process. In addition, the technique of pulsed laser deposition of thin films is extremely versatile since it can provide arbitrary combinations of materials in single and multi-layer thin film form. We have also demonstrated ultra-high quality SnO₂ epitaxial films on sapphire substrates using 700 fx laser ablation deposition.

d. Measurement of ~10 fs XUV Pulses from High-Order Harmonic Generation

Several theories have predicted that attosecond pulses might be generated using high order harmonic generation excited by ultrashort pulses. However, to date the fastest harmonic pulse duration measurements published were performed using laser pulses longer than 25fs. We experimentally demonstrate a cross-correlation measurement which sets an upper limit of ~10 fs on the pulse duration of XUV harmonics.

The high order harmonic pulses are characterized using the laser-assisted photo-emission method. We measured the pulsewidth of the cutoff harmonics, because they should have the fastest temporal emission. For the 21^st harmonic (38 nm) using Xenon gas, the FWHM of the cross-correlation is 34.8 fs using a dressing pulse of 33fs. Deconvolution of the cross-correlation results in an upper limit of 11 fs on the pulse duration. This is the shortest XUV pulse yet reported.

a) The physics issues discussed in B.1.b. overlap many of the same issues that are involved in the generation of coherent keV-energy x-ray light sources. In the case of relativistic scattering, we hope to develop a means to phase-match coherent high-order harmonics. (b) For this and any other laser-based x-ray source to be efficient, channels are required to increase the length of laser propagation, which we hope to extend to centimeter lengths. (c) We will continue our studies of ion acceleration, with an eye towards applications in nuclear physics and radioactive isotope production. (d) In collaboration Robert Crowell and his colleagues from Argonne National Laboratory, we will investigate the applications of sub-picosecond laser driven electron pulses to ultrafast radiation chemistry.

We began a new activity in collaboration with Professor Roy Clarke. An ultrafast kHz CPA has been installed on the MHATT-CAT beam line of the Advanced Photon Source at Argonne National Laboratory, in order to merge ultrafast lasers with undulator x-rays for a number of experiments. Our first experiment will be to excite phonons and use them to gate the synchrotron x-rays. This experiment involves Professor Bucksbaum and CUOS Fellow David Reis.

The following is planned for the Material Research projects: (a) Investigate isotope separation for heavy elements using ultrafast laser ablation, and come to a more complete understanding of the process; (b) Investigate the use of domain epitaxy for high temperature nitride and oxide materials fabrication using ultrafast-pulsed laser deposition; (c) Use the newly developed systems for time resolved materials studies to investigate reversible transformations in materials; (d) Develop double-pulse correlation techniques to study fundamental phenomena in high-energy laser ablation of materials; (e) Investigate optical emission spectra from femtosecond laser induced breakdown (LIBS) for remote identification of metallic alloys; (f) Use a variety of new and conventional techniques to study the physical state of femtosecond laser plasmas as they relate to high-energy and large-area laser ablation processes. The work will include observations of ion energy spectra, Langmuir probe data, optical emission spectra, and isotope separation effects.

Faculty: Tibor Juhasz, Ph.D., Associate Research Scientist, Prof. Ron M. Kurtz, M.D., Karin R. Sletten, M.D., Doug L. Miller, Ph.D., Greg J. Spooner, Ph.D.

Visiting Collaborators: Gagik Djotyan, Ph.D., Research Institute for Particle and Nuclear Physics, Budapest, Hungary; A. Roy Williams, Ph.D, D. Sc, Dept of Medical Biophysics, University of Manchester, Manchester, England, UK.

Clinical Collaborators: Kimberly G. Yen, M.D.

Industrial Collaborators: Christopher Horvath, Ph.D., IntraLase Corporation, Irvine, CA; Laszlo Turi, Ph.D., IntraLase Corporation, Irvine, CA.

Graduate Students: Delia Cabrera, Hsiao-hua Liu, Gabrielle Marre, Marie-Helene Meunier, Zachary S. Sacks.

1. Major Accomplishments

a. First human femtosecond refractive procedures - Replacement of the excimer laser and mechanical blade technologies with ultrashort lasers in refractive surgery is a major goal of the Medical Group. Following recent successes in animal models, refractive procedures using femtosecond laser pulses were performed for the first time ever in humans eyes. Using the parameters developed for intrastromal surgery in animal corneas during the preceding year [47] and two newly-placed prototype clinical units in Europe (IntraLase Corporation), a number of blind and partially-sighted eyes were treated. Lamellar resection, femtosecond laser keratectomy (FLK), and intrastromal vision correction (IVC) procedures were all performed and evaluated. The results indicate that the quality of the cuts as evaluated by examining the corneal flaps (generated in the lamellar resection procedure) are quite good, a result similar to that previously obtained in monkey and rabbit models. A further demonstration of the quality of the cuts has been obtained in the FLK procedure, in which the removal of a lenticule-shaped tissue block produces a strong myopic correction. Finally, in the IVC procedure, hyperopic and myopic corrections were demonstrated. Measurement by a scanning slit refractometer (Orbscan) shows that the corrections, while smaller than those predicted by standard geometric model calculations, have been successfully demonstrated for the first time in human eyes.

b. Demonstration of stable refractive change in primate models - Lamellar resection and IVC procedures in primate models were reported last year [47,48]. Stability of those procedures has been evaluated since those procedures were performed. In addition, histologic examination of the corneas was performed on a number of the treated primates. To summarize the results, corneal clarity was maintained, the endothelium and other structures outside the corneal stroma remain intact, and both the corneal flaps and the IVC-induced corneal thinning are stable for up to 8 months in the animals studied.

c. Development of a analytic model of the biomechanical effects of intrastromal treatment in an ideal cornea - The accepted estimation technique for refractive corrections through the removal of corneal stroma relies on a simple geometric relaxation of the cornea. For small corrections the geometric model is adequate. For large corrections, or for intrastromal treatments, the effects of intraocular pressure, partial (as opposed to complete) collapse of the treated stromal cavity, and the weakening of the mechanical properties of the remaining treated stroma must all be considered. Gagik Djotyan of the Research Institute for Particle and Nuclear Physics in Budapest, Hungary, in collaboration with the Medical Group has developed an analytic shell model to take into account these effects. Early successes of this model include the qualitative prediction of a relatively weak myopic correction in IVC, due to weakening of the central portion of the stroma and excellent quantitative agreement with existing treatment nomograms (in contrast to geometric model predictions which overstate the size of intrastromal corrections.) An example of this latter prediction can be seen in comparing the size of the myopic correction from picosecond laser keratectomy studies.

Insights from these model calculations will guide the development of treatment nomograms for IVC.

d. Demonstration of Photodisruptively-Nucleated Ultrasonic Cavitation.- In collaboration with ultrasound investigators Doug Miller and Roy Williams, we have demonstrated a new effect we refer to as photodisruptively-nucleated ultrasonic cavitation. (PNUC) In PNUC, we use photodisruption to produce microbubbles in tissue, which serve as nuclei for the application of an ultrasonic field. The applied ultrasound field then cavitates the microbubbles, emulsifying the tissue locally. We have used this effect to destroy ex vivo human lenses[67], demonstrating the general phenomenon of PNUC as a potential non- or minimally-invasive surgical technique (i.e. cataract removal.) A patent disclosure has been submitted to the University Technology Management Office and TMO is actively prosecuting the application. A 2-year intramural grant from the School of Medicine and a 1-year intramural grant from the Center for Biomedical Engineering were recently secured to fund pilot studies for this new work.

a. Development of nomograms for IVC treatment of myopia, hyperopia and astigmatism in humans and primates - Feasibility of femtosecond pulses for use in IVC procedures has been demonstrated by the Medical Group at CUOS. A deeper understanding of the biomechanical response of the corneal stroma and the refractive results of that response is needed to guide the development of treatment nomograms for various refractive errors. Our efforts to develop an analytical model of the corneal response have already provided some insights to the nature of the treatments performed to date. Over the next year we will refine our models, and using primarily primate subjects, we will test new treatment nomograms for hyperopia, myopia and astigmatism. A second-generation prototype laser system is under construction at our industrial collaborator site (IntraLase Corp.) and will be shipped to the University of Michigan Kellogg Eye Center this autumn in order to pursue these studies. Meanwhile, investigations will continue with blind or partially sighted patients using first generation clinical devices in place at European sites.

b. Demonstration of stability of femtosecond refractive procedures in humans - While our group has demonstrated the potential for various femtosecond refractive procedures in humans, long term stability of both resections and intrastromal procedures must be established. We will follow over the next year the partially sighted and blind human eyes treated to date to determine the stability of the various intrastromal procedures.

c. Study photodisruption in sclera and scattering tissues using OPA and Yb:glass laser pulses - One goal of our group has been to develop a treatment for glaucoma. In this application ultrafast pulses are focused below the surface of the sclera to create custom channels. It may be possible to design such channels to relieve the elevated intra-ocular pressure characteristic of glaucoma, while avoiding the epithelial and subepithelial scarring and healing response seen at the conjunctiva in traditional filtration surgery. Slower than anticipated debugging and characterization over the last year have delayed the start of photodisruption experiments with the kHz Ti:sapphire/OPA system. Over the next year we will use this system as well as the newly developed high pulse energy Yb:glass laser to optimize the pulse parameters for effective channel ablation in sclera.

We have assembled a simple Ussing chamber for the purpose of characterizing the hydraulic permeability of treated membranes and will use this apparatus to evaluate ex vivo tissue samples.

d. Optimization of the laser and ultrasound parameters in PNUC – A

Our patent application for this new technique will be submitted in October 99.

Faculty: Prof. Theodore Norris, Ph.D., Dr. Anatoly Maksimchuk, Ph.D. Prof. Gerard Mourou, Ph.D., John Nees, Assistant Research Scientist, Prof. Margaret Murnane, Ph.D., Prof. Henry Kapteyn, Ph.D.

Collaborators: Dr. Koshichi Nemoto, Ph.D., Central Research Institute of Electric Power Industry.

Students: Olivier Albert, Seung-whan Bahk, Leah Bruner, Jerome Faure,

Julien Queneuille.

CUOS has made significant progress in the development of high-intensity laser sources during the past year. In this effort, we have concentrated on three factors that determine the focussed intensity; the spatial quality, the temporal quality, and the pulse energy. We have improved the spatial beam quality by correcting wavefront errors at both fundamental and second harmonic wavelengths with a deformable mirror. We have developed a new quasi-one-dimensional membrane mirror to improve temporal pulse definition. We have also continued the development of diode-pumpable high-saturation-fluence materials.

Adaptive compensation for high order phase errors. Compensation for temporal phase errors in high-power laser systems can be accomplished at the front end of a system where the intensity is quite low. CUOS recognized that a new class of deformable mirrors fabricated using microlithography (made by Gleb Vdovin at Technical University of Delft) could be placed into to a 'zero-dispersion' stretcher and used to adaptively compensate high-order phase errors. We employed a genetic algorithm to optimize the configuration of the deformable mirror resulting in correction for high-order phase distortions over 100 nm in two high-power CPA systems. Following a 15 minute optimization cycle reduces the system group delay error to less than 5 fs . The deformable mirror can hold its figure for a full day of laser operation at 15 fs. The same deformable mirror technology was also used to compensate for self-phase-modulation arising from the propagation of a 20 fs pulse in a nonlinear medium.

Modification of temporal phase was also used to enhance the generation of harmonics in hollow-core fibers. By selecting a specific harmonic as the outcome for a genetic algorithm a 50% enhancement of a specific harmonic may be seen. Similarly, the bandwidth resulting from propagation on a hollow core fiber was found to have dependence on input chirp, i.e., a slight positive chirp enhances the self-phase-modulation.

Spatially dispersive amplification. - Gain narrowing is one factor that limits the bandwidth of high-power laser systems. It is generally compensated by injecting a seed with low intensity in the spectral region where gain is highest or by introducing spectrally dependant loss into the amplifier. We proposed and demonstrated spectrally dispersive amplification could be used to directly modify the gain in CPA systems. In a spectrally dispersed amplifier a 'zero-dispersion stretcher is designed into the cavity of a regenerative amplifier. The gain is placed at a point in the cavity where the frequency components are separated. By designing the spatial profile of the pump to produce a flat gain spectral narrowing is avoided.

Amplification in Yb-doped fiber - Diode-pumped Yb doped fibers have been demonstrated to give continuous single-mode power up to 110 W. This striking result is of considerable interest in ultrafast science if short pulses could be amplified in such a system. We previously demonstrated chirped-pulse amplification in single-mode Yb-doped fiber to the level of 10 µJ. The potential exists to achieve this result at a 1 MHz repetition rate, making a directly diode pumped alternative to the 300 kHz Ti:sapphire lasers available today. We have now demonstrated amplification of 100 MHz pulse trains in diode-pumped Yb-doped dual-core fiber.

Our research in the future will stay on the same course: a) development of diode pumped fiber or bulk CPA laser; b) development of techniques to improve the temporal contrast; c) continuing our effort in temporal and spatial phase error correction.

a. Coherent control of normal modes in quantum-well semiconductor microcavity - We have demonstrated the coherent control of the exciton-photon normal modes in a strongly coupled quantum-well semiconductor microcavity using two-color scheme. Coherent excitation of one normal mode using a pair of phase-controlled optical pulses gives rise to a nonlinear response on the other normal mode due to the nonlinearity of the exciton transition underlying the normal modes. The nonlinearity is strongly enhanced due to the field enhancement in the cavity. In our measurement, we found that the dephasing time (T2) is about 2 ps and the origin of the optical nonlinearity in the coherent regime (t<T2) is quite different from that in incoherent regime (t>>T2). The optical nonlinearity in incoherent regime can be by a classical model including excitation induced dephasing (EID). However, the classical model is not capable of explaining the carrier dynamics in coherent regime; instead we find that the nonlinearity originates from Coulomb correlations (coherent biexcitonic effects) which can be understood only beyond the usual Hartree-Fock approximation. We also have discovered that true quantum correlations between the cavity field and the carrier density can be observed in a novel coherent control experiment; long-lived oscillations in the transient reflectivity of a weak probe appear as the result of pump-induced quantum correlations. The phase and amplitude of the intraband coherences can be controlled via the relative phase of the pump pulses. Excellent agreement between the experiments and a fully quantized theory of optical interactions in semiconductors is found. Additionally, in an effort to evaluate the potential of the coherent control for high-speed all-optical switching, we have searched the optimal parameters (pump-probe polarization, cavity detuning, temporal pump pulse separation etc.) to maximize the contrast ratio of the coherent controlled signal. The best results are obtained for cross-circular polarization combination, negative cavity detuning (-0.96meV), and about one picosecond of temporal pump pulse separation.

b. Coherent Control and Spectroscopy of Single Quantum Dots - During the previous reporting period, we summarized our work to obtain the first the high resolution nonlinear laser spectroscopy study on a single quantum dot exciton. Using that work, we then proceeded to show the possibility of coherent optical control and wave function engineering of a single quantum dot exciton on a time scale short compared to the decoherence time in this system. We have now continued this work along two lines. In the first set of experiments, we have worked to make the first demonstration of optically induced electron entanglement. The experiments were done in a single quantum dot where a magnetic field was used to lift the m-degeneracy and restore symmetry. The measurements unambiguously showed the existence of optically induced Zeeman coherence, which in a two-electron system of this type implies two-electron entanglement. The measurements also demonstrated the importance of Coulomb correlations beyond Hartree Fock. In the second class of experiments, we worked to develop the methodology to demonstrate Rabi flopping in a single quantum dot. The measurements showed a Rabi flop in an ensemble state of dots which confirmed our experimental approach.

We are now working to extend these measurements to a single dot.

c. Coherent Phonons - To test the relationship between spontaneous and impulsive stimulated Raman scattering, we performed resonant impulsive measurements on e -GaSe using an optical parametric amplifier through a collaboration with the group of Dr. J. Kuhl of the Max-Planck-Institut FKF (Stuttgart, Germany). Using pulses of central energy E_C in the vicinity of the direct exciton (at E_X »  2.1 eV), we observe oscillations associated with the A₁-symmetry mode at W  »  4 THz. The phonon contribution could be clearly distinguished from the electronic background for energies below ~ E_X + W , but  it becomes harder to separate above that value. The dependence of the phonon amplitude as a function of E_C (not shown) exhibits a sharp resonance for E_C »  E_X  with an enhancement factor of ~ 25 for the vibrational energy. These results are in very good agreement with the spontaneous resonant data and the theory of resonant ISRS, developed by us.

d. Ultrafast Excited State Dynamics in Molecular Systems - Tunable, ultrashort (£ 50 fs) pulses were used to study excited state dynamics in simple polyenes and in photosynthetic systems. Ultraviolet transient absorption spectroscopy was used to study the S₂ ® S₁ and S_1® S₀ internal conversion process in the hexatriene chromophore. The third harmonic of a Ti:Sapphire laser was used to provide both the pump and probe pulses. The third harmonic was generated parametrically in a hollow fiber filled with ca. 65 torr of Argon gas. The resulting pulses were 45 to 55 fs at the sample. These experiments allowed the first direct observation of the S₂ ® S₁ internal conversion in solution. The S₂ ® S₁ internal conversion is 50 ± 20 fs for cis-1,3,5-hexatriene dissolved in cyclohexane and 60 ± 20 fs for trans-1,3,5-hexatriene dissolved in cyclohexane. The subsequent S₁ ® S₀ internal conversions are 250 ± 30 fs and 190 ± 30 fs respectively. Visible ultrashort pulses were generated by recompression of the output of a home-built broad band optical parametric amplifier constructed according to the design of Wilhelm et al. [Wilhelm, T.; Piel, J.; Reidle, E., Opt. Lett. 1997, 22, 1494-1496]. Near transform-limited pulses of 35 to 40 fs at center wavelengths between 665 nm and 685 nm inclusive, were used to study the excited state exciton dynamics in photosystem II reaction centers. The relaxation of the initially excited state is observed on time scales ranging from 60 fs to several ps. The present set of measurements allowed the first observation of the large amplitude, ultrafast (ca. 60 fs) electronic relaxation from the initially excited state to lower energy exiton states of the reaction center core.

e. Ultrafast Optics for Microscopy - In the past year we have made a significant advance in using ultrashort pulses for confocal microscopy. CUOS researchers have previously shown that using adaptively controlled deformable mirrors can significantly improve the focussing of ultrahigh-intensity laser pulses; we have applied this technology to aberration correction in beam-scanning confocal microscopy. In order to avoid the usual problem of wavefront measurement of a beam focussed to a submicron spot, we have used a genetic algorithm to find the globally optimum wavefront correction. In an all-reflective system based on an off-axis parabola, we found an improvement in the scan area by a factor of nine.

a. Coherent control of normal modes in quantum-well semiconductor microcavity - In the coming year, we plan to investigate new samples, as we believe that much higher optical switching contrast will be obtainable with optimized microcavity structures (particularly those exploiting shorter cavity lifetimes). In addition, we will investigate the dynamics of exciton populations in microcavities using a novel combined optical-pump/terahertz-probe experiment.

b. Coherent Phonons - In the next period, we intend to center our attention on resonant studies of coherent phonons in Sb and Cd(S, Se) quantum dots.

c. Ultrafast Excited State Dynamics in Molecular Systems- In the coming year we will continue studies of ultrafast excited state dynamics and solvation dynamics. Replacement of lenses in the current OPA design with curved mirrors will allow a substantial increase in the available bandwidth. Pulses of ca. 20 fs are anticipated. The increased bandwidth will also permit ultrafast spectroscopic measurements of excited state dynamics by dispersing the probe pulse in a grating spectrometer and using multichannel detection. Specifically, studies of PSII, cobalamins, previtamin D₃, and small polyenes, will continue.

d. Ultrafast Optics for Microscopy - In the coming year, we will investigate the use of adaptive optics to correct for aberrations when the beam is focussed deep into tissue, and to increase the depth to which optical tweezers can trap small particles (both of these cases are currently limited by spherical abberations which we should be able to compensate). We will also investigate the use of femtosecond pulses in a novel scheme for harmonic imaging of cells and tissues, in a collaboration with Prof. J. Baker in the Medical School. We will continue to develop the use of multiple-pulse excitation for fluorescence kinetics imaging, as described in last year’s report.

Faculty: Prof. Linda Katehi, Ph.D.Prof. Emmett Leith, Ph.D., Dr. John Whitaker, Ph.D., Prof. Herb Winful, Ph.D.,

Collaborators: Ken Elliott - HRL Laboratories, Dr. Don Harter, Ph.D., - IMRA America,

John Hubert - Lockheed-Martin, Dr. Lee Mirth, Ph.D. - Lockheed-Martin, Prof. Amir Mortazawi (NCSU), Prof. Zoya Popovic, Univ. of Colorado – Boulder, Dr. Greg Sucha, Ph.D. - IMRA America, Steve Thomas III, - HRL Laboratories, Dr. Van Rudd (Picometrix, Inc.), Ph.D., Prof. Todd Weatherford - Naval Postgraduate School , Dr. Warren Wright - Cornell Univ., Ph.D.

Research Fellows: Dr. Gerhard David, University of Duisburg, Germany, I. Papapolymerou, University of Arizona.

Students: Jonathan Berry, Douglas Craig, Matt Crites, Jason Deibel, Simin Feng, Hyungsoo Kim, Heeseok Lee, Victor Perlin, Ron Reano, Alronzo Ruffin, J.-G. Yook (graduate), Joe Allen, Scott Spears (undergraduate), Kyoung Yang,

a. Single-Cycle Terahertz Pulse Propagation - In an experimental collaboration with a small, local company, Picometrix, we have made the first direct, unambiguous, non-interferometric observation of the Gouy phase shift. This phase shift had been predicted by us to result in polarity reversals and temporal reshaping as a terahertz pulse evolves through a focus. By comparing focused and collimated pulses, we have found that the Gouy shift is indeed a geometrical phase that exists over and above any dynamical phase acquired on propagation. In subsequent experiments we were able to manipulate the shape of single-cycle pulses simply by adjusting the accumulated Gouy phase shift imposed by a series of lenses. A paper describing these results has been accepted for publication in Physical Review Letters.

b. Electro-Optic Near-Field Mapping of Quasi-Optic Power-Combining Amplifier Arrays - We have continued to make extraordinary progress in the mapping of the three orthogonal electric-field components in the near-field regime of microwave radiators. In the past year we have demonstrated that ultrafast lasers and electro-optic sampling provide the only means for directly diagnosing failures and characterizing malfunctions present within the important class of microwave antenna systems known as quasi-optic power-combining amplifiers. These components, which hold the promise to replace the large, heavy, tube amplifiers now in use in avionics, typically do not perform according to design, and trial-and-error is the primary means used to improve their performance. We have shown that near-field electro-optic sampling is extremely effective in troubleshooting non-performing unit cells, due to contact or active device failure, as well as design errors in bias networks and phase discrepancies between unit cells induced by surface-wave cross-talk. In fact, within one power-combining amplifier, we have directly observed for the first time electric fields emanating from a microwave circuit that can be attributed to a surface-wave propagation mode.

In addition, for the first time, electro-optic field mapping experiments have been conducted in order to observe electric fields at millimeter-wave frequencies in excess of 100 GHz. Access to this W-band frequency range means that electro-optic field mapping will be an effective tool for characterization of automotive radars and future generations of communications and remote sensing systems.

c. Ultrafast Photoconductive Sampling for Nonlinear Microwave Circuit Characterization - The micromachined photoconductive sampling probe previously developed at CUOS has been demonstrated to be an extremely useful tool in the non-intrusive measurement of signals within nonlinear microwave circuits. In a collaboration with Prof. Zoya Popovic, a microwave analog-circuit expert at the University of Colorado, time-domain measurements using the photoconductive sampling head have been performed on novel, 8-GHz high-efficiency power amplifiers and 1- and 5-GHz frequency doublers.

In high-efficiency class-E and class-F power amplifiers, the transistor is used as a switch and the harmonics of the switched voltage are reflected back towards the transistor before reaching the load. The high-efficiency circuits can also be used to produce frequency doubling. This is done by reflecting the fundamental frequency back to the transistor and presenting the second harmonic with a suitable load.

In order to analyze nonlinear amplifiers designed to deliver a sinusoidal wave to the load, voltages at characteristic points inside the circuit need to be known. If large-signal circuit models are not available for the active devices in the circuit, as is often the case (especially at higher frequencies), or if one would like to confirm the presence of harmonics and the effectiveness of filtering in certain circuit elements, then the ultrafast-optical-based measurement using the photoconductive probe become very valuable. In our measurements on the multipliers, we were able to track the leakage of harmonics, either back towards the microwave input or towards the output. This has helped the microwave engineers to expedite the design cycle, specifically by determining exactly where additional harmonic tuning is required to improve efficiency. In amplifiers, where simply achieving high output power is one way to verify performance, any ambiguity in the specific class of operation has been eliminated through internal waveform measurements. Thus we have validated the design of the amplifiers, and, in this case, shown that the small signal active-device models utilized in the design were sufficient to produce a high-efficiency, nonlinear amplifier.

d. An Extension of Phase Conjugation to Imaging through Scattering Material - Phase conjugation is a long-established and powerful method for imaging through aberrating media. The use of phase conjugation for such imaging was first proposed and demonstrated by Leith and Upatnieks at the University of Michigan in 1965. It would be attractive to use this technique in the currently important area of imaging into biological tissue, an area sometimes known as photon migration or optical coherence tomography. The bar to its usage in this biological problem is that one must have access to the plane of the original object, since the procedure calls for a double transit through the medium. When the object to be imaged is embedded within the object instead of being on one side of it, the method is inapplicable, since one then does not have access to the plane where the corrected image forms. We have proposed and tested a modification of the phase conjugation process. If between the time the distorted wave front is recorded and the time that the readout process is carried out, the medium has been altered in some manner, then the wave front healing process will be degraded. The goal is to measure this degradation.

The phase conjugation process can be carried out by a 4-wave mixing technique or by conventional holography, or by various other phase conjugation methods. Since a time delay between the recording and readout process is required, the phase conjugation process must be one that permits a time delay between the two steps. This delay could be seconds, hours, or even days, depending on the requirements of the application. During this delay time, the scattering medium (biological tissue) is altered in some manner, by tension, heating, etc. The requirement is that the alteration in the scattering property be somehow dependent on the condition of the tissue. The amount of degradation is then an indication of the state, i.e, the health of the tissue.

Experiments were carried out by imaging a point source of light through some scattering medium, and the image produced in the readout process was examined. The image consists of the image of the point, along with some degradations. The degradation can be either a broadening of the image point, or the presence of a halo of light around the point image. Measurement of these degradations is an extremely sensitive indicator of the degradation process. In one such test, a hologram was made of a plane wave passing through two pieces of shower glass separated by a space filled with water. The plane wave on readout was brought to a focus and the image quality measured. A small amount of sugar was added to the water to change its index of refraction. Indeed, very slight changes in refractive index made a measurable difference in the image quality. Similarly, small inclusions in the optical path between the two planes made a difference in the measurement. The data thus collected is still under evaluation.

a. Electro-Optic Field Mapping - We expect that the investigation of surface-wave modes will lead to revelations about the underperformance of quasi-optic power combining arrays, thus leading to the development of millimeter-wave arrays that achieve the output power and phase front intended by their design. We will study the surface-wave-mode propagation by building and testing with the electro-optic field mapping technique a variety of structures that are designed to enhance the surface modes. Through modifications of these structures we will be able to determine steps to take to most effectively diminish the surface modes within the actual power combining arrays.

b. Single-Cycle Terahertz Pulse Propagation - Theoretical work on the spatiotemporal evolution of single-cycle pulses will be extended to include higher order transverse spatial modes as well as the intra-cavity dynamics of these pulses. Experiments on intra-cavity dynamics are also being planned.

c. Terahertz Characterization of Environmental Hazard - Broadband spectroscopy using the free-space-radiating terahertz beams that are generated and detected through ultrafast optoelectronic means has been demonstrated to have great utility in the fields of physics and chemistry. For instance, the complex index of refraction or conductivity of dielectrics and thin metallic or superconducting films have been reliably extracted, and the chemical signatures of gases and liquids have been measured by terahertz spectroscopy in order to identify the compounds. We wish to investigate whether terahertz beams can be used to identify hazardous materials from within contaminated soil samples, preferably through reflection spectroscopy so that such a diagnostic system could be used in the field. Apart from determining what hazardous compounds might be present, it is also essential to know what type of soil is acting as the substrate for the contaminants. Spectroscopy may not be sufficient to identify sandy soil versus clay, for instance, but scattering techniques may, so this approach will be studied to determine if it will be effective for discriminating between soils.

Each year’s experiences leave us increasingly convinced that our outreach programs, if they are to eventually result in more scientists and engineers, must be multifaceted. We must engage children and teens with hands-on science learning experiences in order to capture their interest and foster their success; we must help them explore possible careers so that they will have a natural motivation to pursue technical studies; we must support them directly in those studies, and we must treat them as whole persons, with needs and desires that may take precedence over our narrow goals for them. All of these facets require that we rebuild a learning community around our children, since it takes the efforts and talents of all of us to provide all these services for them. Even the phrase "provide services" is misleading or inexact, since what they really need is the individualized, caring, responsive connections to adults that are offered by an ideal—perhaps mythical—community. And just when the task seems too daunting, we remember that children are also quite capable of taking on responsibility for themselves and others; our Technology and Science Wizards at partner elementary schools have enjoyed and succeeded in sharing computer and experimental skills with their peers and with adults. They are stakeholders, too.

Our major accomplishments can be summarized as follows:

During the coming year, we expect to complete the transformation of our tutoring programs into true mentoring, with consistent relationships and a broader scope of assistance to young people. Specifically, we will be incorporating some degree of career exploration in all these programs. We do not expect our volunteer numbers to continue to grow as rapidly as they have, because of this emphasis on the same people meeting repeatedly over extended time periods.

The major expansion will be an attempt to coordinate hands-on science activities with the Serendipity Reading Clubs at six Ann Arbor Public Housing sites. Reduced transportation difficulties (as compared with programs in Ypsilanti and Pontiac) should foster long-term relationships—and the children are certainly just as needy.

The pilot Research Experiences for Teachers program, while extremely successful in our judgment, focused more on pedagogical than scientific research. While we hope to offer a further-refined version of this year’s program, which served to support all of our programs in the field, we are also planning a more traditional immersion in CUOS research for the exceptional (one or two local high school teachers who want and would profit from that.

This year six students took part in the summer research program for undergraduates at the Center. They were recruited from mostly small colleges like Oberlin, Lycoming, and King College. The three female and three male students were paired with Center faculty according to their areas of research interest. At the end of the 10-week program the students presented their results in a special seminar attended by faculty and students. They also turned in written reports. In addition to the research activities, the students also took part in social events such as such as a trip to the Shakespeare Festival in Stratford, Ontario. The summer program has proven to be a useful recruiting tool for our graduate programs.

This year two former summer research students have enrolled in our graduate programs in Applied Physics and Electrical Engineering.

Several areas of activity were pursued in technology transfer and industry liaison during the past year. These included the following:

GOALI program with C/MXR

Liaison with Panasonic

Huron Valley Steel (HVS) Program

Governor’s State Initiative

Conflict of Interest Committee

(a) Clark/MXR, a local manufacturing company that produces ultrafast lasers and associated equipment has been participating in the use of CUOS technology through a licensing agreement on one of our patents. This activity follows as part of a long history of association with the center. The company, throughout the past year, has been providing assistance to the center in the form financial contributions. This support has been in the form of unrestricted gifts (~ $30K) with the intention of helping the center in its applications research. As a follow on to that interest we collaborated with them in writing a GOALI proposal ($424K) to the NSF. The outcome of this proposal is still pending. Regular meetings are held with key individuals from the company in order to assess and evaluate new technology emerging from the center; (b)Liaison with Panasonic Corporation has been established during the past year. They have a continuing interest in applications of femtosecond lasers to micromachining. As part of establishing a connection with us, they have donated $20K as an unrestricted gift to the center. We look forward to developing a closer working arrangement with them as time progresses; (c)Huron Valley Steel is a local company that uses laser ablation technology as a way to identify and sort recycled metal in a high throughput environment. Their approach is to use a focused laser beam to produce an ablation plume from the surface of metallic alloys as they move along on a conveyor belt. The vapor plume emits optical radiation that is characteristic of the alloy being probed. A detector system identifies the alloy and sorts the part into a bin that is specified for that particular alloy. They are developing the use of conventional lasers for this purpose and wish to extend their technology to the use of ultrafast lasers. We have an ongoing program with them that involves $23K for use of our lasers in areas of interest to them; (d)Governor Engler has recently established the Governor’s Innovation Forum as a mechanism to help couple Michigan’s research universities with high technology companies in the state. We have maintained a close watch on these activities and participated in several discussion meetings with key individuals prior to and during the yearlong multi-meeting forums. Our intent was to project U of M interests and CUOS capabilities into these meetings and to maintain a detailed understanding of the progress of the policies that were forthcoming from the discussions. This has been a very interesting experience and of high potential benefit to CUOS. It is anticipated that state funds will become available as matching funds for new technology initiatives, and as direct state support for new commercial development of emerging technology. It is our intention to apply for such funds as soon as is practicable;

(e) This year has involved meetings with the UM Conflict of Interest (COI) Committee discussing issues related to CUOS technology transfer activities. This committee has elevated its awareness of issues involving potential conflicts of interest within the university and has expressed to CUOS its desire for continuing input and background information on such potential conflict of interest issues. We continue to work with them on this topic and to advise faculty in CUOS on this subject and their responsibility in that regard.

It is anticipated that technology transfer activities at CUOS will continue along lines similar to those of past years with the added dimension of being more integrated with the broader strategies of other similar programs within and across the College of Engineering. A significant part of our liaison and transfer activities relate to educating and assisting faculty in regard to their involvement with the tech transfer process. Assisting faculty in submitting new patents and developing ongoing research into patentable concepts requires such a steady process of encouragement and support. We are ever mindful in pursuing such goals that opportunity for spin off companies can and will present itself for further development. As you know, such opportunities are vigorously pursued when they are identified. In addition, we continue to investigate and promote sponsored research activities with outside companies as they seek to participate in the technological developments at CUOS. We are presently working with three companies in this regard and have obtained initial financial support from them in the form of gifts and small project support. It is our intention to develop these into larger and more significant activities definable through sponsored programs. A notable new development at the state level has been the Governor’s Innovation Forum, which seeks to couple Michigan industry with research universities in the state. We have maintained close watch on these activities and have participated in the forum process as it evolved over the past year. It is our intention to maintain a continued close involvement with this program and to submit proposals for state support of our commercialization projects and to investigate the accessibility to matching state funds in our evolutionary CUOS renewal proposals.

This year the Fellows and Visitors program had an active and varied program. We supported nine fellows, covering the areas of interest to CUOS, including ultrafast optics, high field physics, chemistry, and light source development. Of particular note are areas where fellows program support has been instrumental for new program development. Here we note the hiring of Victor Yanovsky from Livermore, for support of the high intensity and high average power laser projects; David Reis, for support of a new collaborative project on ultrafast x-rays with the Michigan beam line at the APS; and Julien Queneuille, for projects in collaboration with ENSTA.

This year we continued our joint NSF/CNRS collaboration. We are in the second year of an NSF international collaborative grant, which supports one French post-doc, Albert Olivier, at CUOS. The Fellows program administers this.

The Fellows program sponsored two collaborative workshops in the past year. First, we supported in part a joint CUOS/ENSTA Rendez-Vous in Palaiseau, France. The second workshop was SILAP V, the fifth conference on Super-Intense Laser-Atom Physics, which was held at American University as a satellite of CLEO last spring.

Finally, the Visitors program supported approximately 30 visits by outside scientists to CUOS, for collaborations, seminars, and independent work. These scientists come from all over the world, and our ability to support their visits is one of the prime outreach activities toward our colleagues in the international research community.

CUOS high-intensity short pulse Ti:sapphire/Nd-phosphate glass laser (T-cube) has been extensively used for plasma physics studies at relativistic intensities, for the development of x-ray and XUV ultrafast sources and for development of the laser itself. Table 1 presents the parameters of this laser.

_______________________________________________________________________

Energy (J) 4 1.5

Pulse Width (fs) 400 400

Contrast Ratio 106 1010

Laser Flux (W/cm2) 4x1019 1x1019

Repetition Rate (Hz) 0.002 0.002

_______________________________________________________________________

Table 1: Laser parameters

This year we continued the studies in plasma physics at relativistic intensities, which includes self-channeling and self-guiding of high-intensity short laser pulse [7,58], observation of nonlinear Thomson scattering [57], acceleration of ions to MeV energies from gas [19,58] and solid targets. In the field of ultrafast x-ray and XUV plasma sources we studied an influence of high strength oscillating fields on ion electronic structure [18]. These high fields are achieved in either of two ways: (1) by the field of unscreened ion charges in a plasma (≈ 10⁹ V/cm), which result in strongly coupled effect such as continuum lowering, line broadening and line merging, or (2) by the high electromagnetic field on an intense laser (≈ 10¹¹ V/cm), which results in the formation of laser satellites around forbidden x-ray lines. The work on a laser development includes a wave-front correction of the frequency doubled light in type I or type II KDP crystals. We were able to increase a focused laser intensity more than two times while maintaining a high-intensity contrast ratio of the pulse. We also demonstrated a significant laser pulse shortening to

≈ 50fs of a frequency doubled light using KDP type II crystal with a predelay.

Experiments conducted on T-cube facility are the result of collaboration between scientists, postdocs and graduate students from CUOS with leading scientists and specialists around the world. Experiments [19,57,7,58] were performed by the CUOS HFS group in collaboration with the scientists from P. N. Lebedev Physics Institute (Russia). Work [18] was carried out in a collaboration with the group of Prof. J. K. Kieffer (INRS, Canada), who provided subpicosecond x-ray streak camera. Multi-Charged Ion Spectral Data Center from Moscow Region (Russia) provided x-ray spherically bent crystals for this experiment. Experiments with deformable mirror were performed in collaboration with scientists and postdocs from CUOS, Laboratoire d'Optique Appliquée, Paris (France) and Central Research Institute of Electric Power Industry, Tokyo (Japan).

Within the UFT area, the Center has supported the development of an experimental station for conducting measurements of ultrafast electrical waveforms via electro-optic sampling. This high-bandwidth signal-measurement facility utilizes miniaturized electro-optic crystals in a Pockels cell modulator configuration in order to measure electric-field-induced changes in the transmission of 100-fs laser pulses that are on the order of 1 part in 10⁷.

A 30-TW laser, currently the most intense at a U.S. university, was built and used for a variety of experiments, on clusters (Kapteyn), plasmas (Umstadter) and gases (Murnane). Although most of the results are preliminary, many of the issues associated with handling such high power levels were addressed and some novel results are emerging. Several projects funded by single-investigator grants from DOE and NSF benefited from access to this unique facility: (1) "Atomic Processes in High-Energy-Density Plasmas," Division of Chemical Sciences, Office of Basic Energy Sciences, Office of Energy Research, U.S. Department of Energy, D. Umstadter, P.I.; (2) "An All Optical Laser Wakefield Electron Injector" supported by the Division of High Energy Physics, Office of Energy Research, U. S. Department of Energy D. Umstadter, P.I., ; (3) "Relativistic Nonlinear Optics," NSF PHY 972661, D. Umstadter, P.I.; (4) "Ultrafast Laser Producted Microstructured Plasmas for Soft X-ray Lasers" supported by NSF ECS 9713254, H. Kapteyn, P.I.; (5) "Enhanced Ultrafast X-ray Generation Using Pulse Shaping" supported by NSF ECS 9616079, M. Murnane, P.I.; (6) "Ultrafast Dynamics Probed by X-ray" supported by NSF DMR 9753219 M. Murnane, P.I.

The Medical Group has spent considerable effort in the development of a kilohertz Ti:sapphire laser engine and optical parametric amplifier intended for use in several Medical Group projects, Center projects and biological projects with collaborators outside of the Center. This laser system and lab are nearly completed.

Several biologic and medical collaborative experiments have been performed with lasers in the Medical Group and elsewhere in the Center. Investigations using CUOS lasers with researchers outside the Center include the ablation of nerve axons for the investigation of their mechanical properties (Asst. Prof. Ann-Marie Sastry) and the ultrasonic/ultrafast experiments (performed with Senior Research Scientist Doug Miller of the Dept. of Radiology and Prof. Roy Williams of the University of Manchester.)

The main issues this year have been the construction and management of the MRI lasers and the addition of new disciplines at CUOS, namely, materials science and bioengineering. In 1997, NSF awarded CUOS with a substantial Major Research Instrumentation (MRI) grant to set up two state-of-the-art lasers. One laser will deliver high intensities—1016 W/cm2 at 1 kHz; the other will provide intensities >1021 W/cm2 at a fraction-of-a-hertz repetition rate. The construction of these lasers was complicated by the departure of Professors Murnane and Kapteyn, who were in charge of the development and implementation of these lasers. The next year’s priority will be the implementation of these lasers. They will be under the responsibility of Dr. V. Yanovsky for the 0.1-Hz and Z. Chang for the kilohertz. Dr. Yanovsky was hired from Livermore and Dr. Zang, formerly with the Murnane and Kapteyn group, stayed at CUOS. They both have solid experience in femtosecond lasers. We expect that the two lasers will run at their nominal values next year for the kilohertz and around March 2000 for the 0.1-Hz. We took advantage of the Murnane and Kapteyn move to renovate the space to include better air conditioning and more space for the users, and to accommodate future upgrades.

As far as faculty are concerned, we have a strong involvement from faculty in the various areas of science, engineering and medical. It is very gratifying and I will continue to foster these collaborations. We also hope to replace H. Kapteyn by a faculty well established in ultrafast science. Excellent candidates are interested by this position.

As part of a new building addition adjacent to CUOS, we will acquire 2000 sq. ft. of new laboratory space. This new space will become available in 18 months. CUOS needs to support new areas, which could have the greatest potential. To that effect, the management is providing constant support, until they can find their own, to new areas like material sciences and bioengineering. For instance, after three years of support from CUOS and an equipment grant from AFOSR, our materials science group is fully operational and is breaking new ground in isotope separation and thin-film growth. Also, CUOS believes in the impact of micromachining in the life sciences—especially in biochip fabrication, so we will continue to invest in this area.

One of the problems that CUOS is facing is support for the Technology Transfer Office, Dr. Pronko. Originally this office, which has been very instrumental in supporting the creation of three spin-off companies, was jointly supported by the College of Engineering and the State of Michigan. This support has disappeared and CUOS must find the funds to support half the position. Dr. Pronko works half-time as the Associate Director for Technology Transfer and half-time as a senior research scientist in charge of the materials science program.

But the primary CUOS objective is to cope with its sunset scheduled in two years. CUOS has a superb array of interdisciplinary activities built over the past 10 years. We think that it will constitute the foundation of an Institute for Ultrafast Optical Science. This Institute could be composed of five laboratories, in High Field Science, Ultrafast Science, Ultrafast Optics and Electronics, Materials Science, and Medical/ Bioengineering. Each area is today well established and led by a scientist /faculty member who is considered a world expert. We are convinced that by the time of the sunset, each laboratory will be capable of finding most of its funding from various agencies. We envision that this Institute could receive a significant fraction of its funding through NSF and NIH; this block grant will provide the base funding to each laboratory, enhancing the ability of each to attract funds from other sources.

Abrams, Richard, Chief Scientist, Hughes Research Laboratories, Malibu, CA.

Buck, William, Department of Physics, Hampton University, Hampton, VA.

Capasso, Federico, Head, Quantum Phenomena and Device Research Department, Bell Labs

Innovations, Murray Hill, NJ.

Clarke, Roy, Director, Applied Physics Program, University of Michigan, Ann Arbor, MI.

Freeman, Richard R., Head, Lawrence Livermore National Laboratory, Livermore, CA Hochstrasser, Robin, Donner Professor of Chemistry, University of Pennsylvania,

Philadelphia, PA

Holzrichter, John F., Lawrence Livermore National Laboratory, Livermore, CA

Ippen, Erich P., Elihu Thomson Professor of Electrical Engineering, Massachusetts Institute

of Technology, Cambridge, MA

Johnson, Anthony M., Chair, Department of Physics, New Jersey Institute of Technology,

University Heights, NJ

Khargonekar, Pramod, Chair, Electrical Engineering and Computer Science, University of

Michigan, Ann Arbor, MI

Miller, Donna, Michigan Strategic Fund, Michigan Department of Commerce, Lansing, MI

Powell, Howard T., Lawrence Livermore National Laboratory, Livermore, CA

Scott, Derrick, Director, Office of Minority Engineering Programs, University of Michigan,

Ann Arbor, MI

Shank, Charles V., Director, Lawrence Berkeley Laboratories, Berkeley, CA

Sprangle, Phillip, Head, Beam Physics Branch, Naval Research Lab, Washington DC

Tournois, Pierre, Thomson-CSF, Paris, France

Mourou, Gérard, CUOS Director

Bucksbaum, Philip, High-Field Science Representative

Winful, Herbert, Optics Representative

Nees, John, Ultrafast Optics Representative

Norris, Ted, Ultrafast Science Coordinator

Whitaker, John, Ultrafast Tecnology Coordinator

Umstadter, Donald, High-Field Science Coordinator

Maksimchuk, Anatoly, High-Field Technology Representative

Winick, Kim, Ultrafast Technology Representative

Merlin, Roberto, Ultrafast Science Representative

Winful, Herbert, CUOS Associate Director for Education

LaSovage, Jeannine, CUOS K-12 Education Coordinator

Nees, John, CUOS Assistant Research Scientist

Scott, Derrick, Director, Office of Minority Engineering Programs, University of Michigan

Davis, Cinda-Sue, Women in Science Program, Center for the Education of Women,

University of Michigan

Debra McCartney, Undergraduate Student, EECS, University of Michigan

Arti Raheja, Graduated in June 1998, University of Michigan

Mourou, Gérard, CUOS Director, ex officio

1. K.Yang, G.David, S.V.Robertson, J.F.Whitaker, Linda P.B.Kathehi, "Electrooptic mapping of near-field distributions in integrated microwave circuits." IEEE Trans.Micro. Theory Tech., 46, No. 12, December 1998.
2. G.David, T-Y Yun, M.H. Crites, J.F. Whitaker, T.R. Weatherford, K. Jobe, S. Meyer, M.J. Bustamante, B. Goyette, S. Thomas III, K.R. Elliott, "Absolute potential measurements inside microwave digital IC's using a micromachined photoconductive sampling probe." IEEE Trans. Micro. Theory Tech., 46, No. 12, December 1998.
3. G.A. Mourou, C. P. J. Barty, M. D. Perry, " Ultrahigh-intensity lasers: physics of the extreme on a tabletop." Physics Today, January 1998.
4. J.Faure, J. Itittani, S. Biswal, G. Cheriaux, L.R. Bruner, G. C. Templeton, G. Mourou, "A spatially dispersive regenerative amplifier for ultrabroadband pulses" Optic Commun 159 (1999) 68-73.
5. G.Mourou "Ultrahigh-intensity lasers: nonlinear optics in the relativistic regime for future applications in time-resolved chemistry," J. of Chem. Edu. 75, pp. 565-570 (1998).
6. S. Smith, N.C.R. Holme, B. Orr, R. Kopelman and T. Norris, "Ultrafast measurement in GaAs thin films using NSOM", Ultramicroscopy 71, pp. 213-223 (1998).
7. S.-Y. Chen, G.S. Sarkisov, A. Maksimchuk, R. Wagner and D. Umstadter, "Evolution of a plasma waveguide created during relativistic-pondermotive self-channeling of an intense laser pulse", Phys. Rev. Lett., 80, pp. 2610-2613 (1998).
8. K.Yang, G.David, S.V.Robertson, J.F.Whitaker, Linda P.B.Kathehi, "Electro-optic mapping of near-field distributions in integrated microwave circuits." IEEE Trans. on Microwave Theory and Tech., 46, No. 12, December 1998.
9. J.Faure, Jiro Itittani, S. Biswal, G. Cheriaux, L.R. Bruner, Glen C. Templeton, Gerard Mourou, " A spatially dispersive regenerative amplifier for ultrabroadband pulses" Optic Commun. 159 (1999)68-73
10. J.J. Shiang, H.J. Liu and R.J. Sension, "Vibrational relaxation of I2 in complexing solvents: The role of solvent-solute attractive forces," J. Chem. Phys. 109, 9494-9501 (1998).
11. N.A. Anderson, S.H. Pullen, L.A. Walker II, J.J. Shiang and R.J. Sension, "Ultrafast polyene dynamics in solution: The conformational relaxation and thermalization of highly excited cis-1,3,5-hexatriene," J. Phys. Chem. A 102, 10588-10598 (1998).
12. A.B. Ruffin, J.V. Rudd, S. Feng, H.G. Winful, and J.F. Whitaker, "Phase manipulation of a free-space THz beam system using transmissive optics," in Ultrafast Electronics and Optoelectronics, OSA Technical Digest (Optical Society of America, Washington, DC, 1999), pp. 17-19.
13. J.F. Whitaker, G. David, and M. Crites, "Integrated-circuit diagnostics using micromachined photoconductive-sampling probes," in Ultrafast Electronics and Optoelectronics, OSA Technical Digest (Optical Society of America, Washington, DC, 1999), pp. 24-26.
14. K. Yang, G. David, W. Wang, T. Marshall, M. Forman, L.W. Pearson, Z. Popovic, L.P.B. Katehi, and J.F. Whitaker, "Electro-optic field mapping of quasi-optic power-combining arrays," in Ultrafast Electronics and Optoelectronics, OSA Technical Digest (Optical Society of America, Washington, DC, 1999), pp. 30-32.
15. D. Craig, J. Whitaker, G. Sucha, and D. Harter, "Measurements of a compact, fiber-based, ultrafast, laser source," in Ultrafast Electronics and Optoelectronics, OSA Technical Digest (Optical Society of America, Washington, DC, 1999), pp. 47-49.
16. K. Yang, G. David, S. Robertson, J.F. Whitaker, and L.P.B. Katehi, "Electro-optic mapping of near-field distributions in integrated microwave circuits," IEEE Trans. Microwave Theory Tech., vol. 46, pp. 2338-2343 (Dec. 1998).
17. G. David, K. Yang, W. Wang, L. W. Pearson, J.F. Whitaker, and L.P.B. Katehi, "3D near-field analysis of a 4x4 grid oscillator using an electro-optic field imaging system," Proceedings of the 28th EuMC'98, October 1998, Amsterdam, The Netherlands, 1, pp. 346-351.
18. A. Maksimchuk, M. Nantel, G. Ma, S. Gu, C. Y. Cote, D. Umstadter, S. A. Pikuz, I. Yu. Skobelev, A. Ya. Faenov, "X-Ray radiation from matter in extreme conditions," J. Quant. Spectrosc. Radiat. Transfer., accepted for publication (1999).
19. S. Sarkisov, V. Yu. Bychenkov, V. N. Novikov, V. T. Tikhonchuk, A. Makismchuk, S. -Y. Chen, R. Wagner, G. Mourou and D. Umstadter, "Self-focusing, channel formation and high-energy ion generation in interaction of an intense short laser pulse with a He jet,'' Phys. Rev.E 59 7042 (1999).
20. S. Y. Chen, M. Krishnan, A. Maksimchuk and D. Umstadter, "Acceleration of electrons in a self-modulated laser wakefield,'' Advanced Accelerator Concepts: Eighth Workshop, edited by W. Lawson, C. Bellamy, and D. Brosius, AIP Conference Proceedings 472 (AIP Press, New York, 1999), p. 333.
21. K. Kim and D. Umstadter, "Cold relativistic wavebreaking threshold of two-dimensional plasma waves,'' Advanced Accelerator Concepts: Eighth Workshop, edited by W. Lawson, C. Bellamy, and D. Brosius, AIP Conference Proceedings 472 (AIP Press, New York, 1999), p. 404.
22. E. Dodd, J. K. Kim and D. Umstadter, "Electron injection by dephasing electrons with laser fields,'' Advanced Accelerator Concepts: Eighth Workshop, edited by W. Lawson, C. Bellamy, and D. Brosius, AIP Conference Proceedings 472 (AIP Press, New York, 1999), p. 886.
23. D. Umstadter, "Nonlinear optics above the power threshold for relativistic self-focusing," Technical Digest. Summaries of Papers Presented at the Conference on Lasers and Electro-Optics, 3-8 May 1998; San Francisco, CA, Conference Edition. 1998 Technical Digest Series, 6 (IEEE Cat. No.98CH36178). (Opt. Soc. America, Washington, DC, USA; 1998) 559 pp. 197-8.
24. N. H. Bonadeo, D. G. Steel and R. Merlin, "Stress effects in GaAs: Anomalous selection rules and heavy-light hole beats," accepted for publication in Phys. Rev. B. (1999).
25. P. H. Bucksbaum and R. Merlin, "The phonon Bragg switch: A proposal to generate sub-picosecond x-ray pulses," Solid State Commun. 111, 535-539 (1999).
26. T.B. Norris, "Excitons in strongly coupled microcavities," in Semiconductor Quantum Optoelectronics: From Quantum Physics to Smart Devices, ed. by A. Miller and D. Finlayson (Institute of Physics, 1999).
27. P. Bhattacharya, K. Kamath, J. Singh, D. Klotzin, J. Phillips, H.-T. Jiang, N. Chervela, T. Norris, and T. Sosnowski, "In(Ga)As/GaAs self-organized quantum dot lasers: DC and Small-Signal Modulation Properties," IEEE Trans. Electron Devices 46, 871 (1999).
28. A.H. Buist, G.J. Brakenhoff, M. Muller, T.B. Norris, J. Squier, C.J. Bardeen, V.V. Yakovlev, and K.R. Wilson, "Ultrafast lasers and biological applications: from 2-photon to molecular relaxation imaging," in Commercial Applications of Ultrafast Lasers, ed. By M.K. Reed, Proceedings of SPIE-The International Society for Optical Engineering, 3269 , 94 (1998).
29. A. Braun, T. Sosnowski, S. Kane, P. van Rompay, T. Norris, and G. Mourou, "Tunable third-order phase compensation by refraction from an intra-grating-pair parallel plate," IEEE J. Sel. Topics Quant. Electron. 4, 426 (1998).
30. Larsson, Z. Chang, E. Judd, P. Heimann, A. Lindenberg, H.Kapteyn, M. Murnane, R. Lrr, A. Machachek, H. Padmore, R. Falcone, "Ultrafast time-resolved x-ray diffraction detected by an averaging mode streak camera", Proc. OSA Conference on Generation and Applications of High Field and Short Wavelength Sources, Santa Fe, NM (Plenum, New York, 1998) pp. 267.
31. Rundquist , Z. Chang, J. Zhou, H.C. Kapteyn, M.M.Murnane, "Coherent, tunable, x-ray emission at 5nm using high harmonic generation", Proc. OSA Conference on Generation and Applications of High Field and Short Wavelength Sources, Santa Fe, NM (Plenum, New York, 1998) pp. 45.
32. Durfee, A. Rundquist , Z. Chang, J. Zhou, H.C. Kapteyn, M.M.Murnane, "Phase matching techniques for short wavelengths", Proc. OSA Conference on Generation and Applications of High Field and Short Wavelength Sources, Santa Fe, NM (Plenum, New York, 1998) pp. 71.
33. S. Backus, C. Durfee, H.C. Kapteyn, M.M.Murnane, "High average power TW laser system", OSA Conference on Generation and Applications of High Field and Short Wavelength Sources, Santa Fe, NM (Plenum, New York, 1998) pp. 17.
34. I.P. Christov, M.M. Murnane, H.C. Kapteyn, "Dispersion-controlled hollow core fiber for phase matched harmonic generation ", Optics Express 3, 360 (1998).
35. I.P. Christov, M.M. Murnane, H.C. Kapteyn, "Generation of single-cycle attosecond pulses in the vacuum ultraviolet", Optics Commun. 148, 75 (1998).
36. I.P. Christov, V.D. Stoev, M.M. Murnane, and H.C. Kapteyn, "Absorber-assisted Kerr-lens mode locking," JOSA B 15, p. 2631-2633 (1998).
37. C.G. Durfee, A. Rundquist, S. Backus, Z. Chang, C. Herne, H.C. Kapteyn, and M.M. Murnane, "Guided-wave phase-matching of ultrashort-pulse light," J Nonlinear Opt. Phys. 8, p. 211-214 (1999).
38. Margaret Murnane and Henry Kapteyn, "Ultrafast coherent x-ray sources", invited paper, to be published in Reviews of Modern Physics, (1999).
39. Henry Kapteyn and Margaret Murnane, "Ultrafast optics: Life in the fast lane", invited paper, Physics World 12, 31 (1999).
40. Zeek, K. Maginnis, S. Backus, U. Russek, M. Murnane, G. Mourou, H. Kapteyn, and G. Vdovin, "Pulse compression by use of deformable mirrors," Opt. Lett. 24, p. 493-5 (1999).
41. C.G. Durfee, S. Backus, H. Kapteyn, and M. Murnane, "Intense 8-fs pulse generation in the deep ultraviolet," Opt. Lett. 24, p. 697-699(1999).
42. A.C. Tien, S. Backus, H. Kapteyn, M. Murnane, and G. Mourou, "Short-pulse laser damage in transparent materials as a function of pulse duration," Phys. Rev. Lett. 82, p.3883-6 (1999).
43. Durfee, A. Rundquist, S Backus, C. Herne, M. Murnane, and H. C. Kapteyn , "Phase matching of high-order harmonics in hollow waveguides", to be published in Physical Review Letters.
44. P.P. Pronko, P.A. VanRompay, Z. Zhang, and J.A. Nees, "Isotope enrichment in laser-ablation plumes and commensurately-deposited thin films", Phys. Rev. Lett. 83, 2596 (1999).
45. Z. Zhang, P.A. VanRompay, J.A. Nees, R. Clarke, X. Pan, and P.P. Pronko, "Nitride film deposition by femtosecond and nanosecond laser ablation in low pressure nitrogen discharge gas", Proceedings of the European Materials Research Society Conference, Strasbourg, France (June1-4, 1999). Elsevier/North Holland Publishing Co. (in press).
46. P.P. Pronko, P.A. VanRompay, C. Horvath, F. Loesel, T. Juhasz, X. Liu, and G. Mourou, "Avalanche ionization and dielectric breakdown in silicon with ultrafast laser pulses", Phys. Rev. B 58, 2387-2390 (1998).
47. R. Kurtz, G. Spooner, K. Sletten, K. Yen, S. Sayegh, F. Loesel, C. Horvath, H-H Liu, V. Elner, D. Cabrera, M. H. Meunier, Z. Sacks, T. Juhasz, "Femtosecond laser corneal refractive surgery", SPIE Proceedings, 1999:3591
48. R. Kurtz, G.J.R. Spooner, K. Sletten, K. Yen, S. Sayegh, F. Loesel, C. Horvath, H.-H. Liu, V. Elner, D. Cabrera, M. -H. Meunier, Z. Sacks, T. Juhasz, D. L. Miller, A. R. Williams, "Ophthalmic applications of femtosecond lasers", SPIE Proceedings, 1999:3610
49. T. Juhasz, F. H. Loesel, R. M. Kurtz, C. Horvath, J. F. Bille, G. Mourou, "Corneal refractive surgery with femtosecond lasers", IEEE Journal of Selected Topics in Quantum Electronic on Lasers in Medicine and Biology, 1999.(In Press).
50. N. H. Bonadeo, J. Erland, D. Gammon, D. Park, D.S. Katzer, D.G. Steel, "Coherent optical control of the quantum state of a single quantum dot" Science 282, 1473 1998.
51. N. H. Bonadeo, G. Chen, D. Gammon, D.S. Katzer, D. Park, D.G. Steel, "Nonlinear nano-optics: Probing one exciton at a time," Physical Rev. Lett. 81, 2759, 1998.
52. N. H. Bonadeo, A. S. Lenihan, G. Chen, J. R. Guest, D. G. Steel D. Gammon, D. S. Katzer and D. Park, "Single quantum dot states measured by optical modulation spectroscopy," in press, Appl. Phys. Lett. 1999.
53. Erland, J.C. Kim, N.H. Bonadeo, and D.G. Steel, D.S. Katzer, and D. Gammon, "Non-exponential photon echo decays from nanostructures: Strongly and weakly localized degenerate exciton States," in press, Phys. Rev. B, Rapid Communications 1999.
54. P.R. Berman and D.G. Steel, "Coherent optical transient," in press in Laser Handbook (1999). Invited Papers with Published Proceedings N. H. Bonadeo, J. Erland, Gang Chen and D. G. Steel, "Coherent optical excitation of single excitons in quantum dots," invited paper IQEC'98, OSA Technical Digest 7 , p161-162 1998.
55. Erland, J.C. Kim, D. Gammon, D.G. Steel, "Biexponential decoherence in photon echoes: Spectral evidence for nearly degenerate localized excitons.", IQEC '98, OSA Technical Digest 7 p. 210-211, 1998.
56. Erland, N.H. Bonadeo, D. Gammon, and D.G. Steel, "Coherent control of a quantum dot exciton wave function", EQEC 98, 14-18 September 1998, Glasgow, Scotland, Post Deadline Paper EPD2.5.
57. S. -Y. Chen, A. Maksimchuk and D. Umstadter, "Experimental observation of relativistic nonlinear Thomson scattering," Nature 396, 653, 1998.
58. Maksimchuk, G. Gu, K. Flippo, D. Umstadter, G. S. Sarkisov, V. Yu. Bychenkov, V. N. Novikov and V. T. Tichonchuk, "Pondermotive acceleration of ions by relativistically self-focused high-intensity short laser pulse," Proceedings of the 1999 IEEE Particle Accelerator Conference, March 27 – April 2, 1999, New York, USA (IEEE, Piscatway, NJ, 1999), v.5, pp.3716-3718.
59. S. Sarkisov, V. Yu. Bychenkov, V. N. Novikov, V. T. Tikhonchuk, A. Maksimchuk, S. Y. Chen, R. Wagner, G. Mourou and D. Umstadter, ''Self-focusing, channel formation and high-energy ion generation in the interaction of an intense short laser pulse with a He jet,'' Phys. Rev. E 59 7042, 1999.
60. M. Nantel, J. Itatani, A. D. Tien, J. Faure, D. Kaplan, M. Bouvier, T. Buma, Pl Van Rompay, J. Nees, P. P. Pronko, D. Umstadter and G. Mourou, "Temporal Contrast in Ti:Sapphire Lasers: Charcaterization and Control", IEEE J. Selected Topics Quant. Electron. 4, 449-458, 1998.
61. S.-Y. Chen, M. Krishnan, A. Maksimchuk, R. Wagner, and D. Umstadter, "Detailed dynamics of electron beams self-trapped and accelerated in a self-modulated laser wakefield," accepted for publication in Physics of Plasmas, 1999.
62. M. Nantel, G. Ma, S. Gu, C.Y. Cote, J. Itatani, and D. Umstadter, "Pressure ionization and line-merging in strongly-coupled plasmas produced by 100-fs laser pulses,'' Phys. Rev. Lett. 80, 4442, 1998.
63. P. Gallant, Z. Jiang, C.Y. Chien, P. Forget, F. Dorchies, J.C. Kieffer, H. Pepin, O.Peyrusee, G. Mourou, A. Krol, "Spectroscopy of solid density plasmas generated By irradiation of thin foils by a fs laser", Journal of Quantiative Spectroscopy and Radiative Transfer, No. 1014, 5/27/99.
64. B. Ruffin, J. V. Rudd, H. G. Winful, S. Feng, and J. F. Whitaker, "Direct observation of the Gouy phase shift with single-cycle terahertz pulses," Phys. Rev. Lett., to be published, October 18,1999.
65. S. Feng and H. G. Winful, "Spatiotemporal transformation of isodiffracting ultrashort pulses by nondispersive quadratic phase media," J. Opt. Soc. Am. A, to be published, October 1999.
66. S. Hunsche, S. Feng, H. G. Winful, A.Leitenstorfer, M. C. Nuss, and E. P. Ippen, "Spatiotemporal focusing of single-cycle light pulses," J. Opt. Soc.Am. A 16, 2025 (1999)
67. S. Feng, H. G. Winful, and R. W. Hellwarth, "Spatiotemporal evolution of focused single-cycle electromagnetic pulses," Phys. Rev. E 59, 4630 (1999).

1. "Photodisruptive Laser Nucleation and Ultrasonically-Driven Cavitation of Tissues and Materials", Ron M. Kurtz, Gregory J. R. Spooner, Douglas L. Miller, Alun R. Williams, disclosed to the University of Michigan Technology Management Office and in preparation for submission.
2. Provisional Patent submitted to the US Patent Office on 3/24/99, "Method for Laser Induced Isotope Separation", Peter P. Pronko, Paul A. VanRompay, John A. Nees, and Zhengu Zhang. Submitted through the University of Michigan Technology Management Office.
3. "Ultrafast Coherent Phonon Bragg Modulator for X-rays", Roberto Merlin and Philip Bucksbaum have had discussions for a patent (UM #1628) with the University of Michigan Technology Management Office.
4. "Guided Wave Methods and Apparatus for Nonlinear Frequency Conversion", Charles Durfee, and Andrew Rundquist was submitted (UM #1531) to the University of Michigan Technology Management Office.

Graduates Destination

Biswal, Subrat Lawrence Livermore National Lab.

Bonadeo, Nicolas Bell Labs

Dodd, Evan UCLA, Physics Dept.

Krishnan, Mohan Ford Motor Company

Lai, Richard Picometrix

Lotz, Paul Trialon Corporation/Delphi-Delco

Tien, An-Chun Intralase

Yun, Tae-Yeoul Texas A & M University

David, Gerhard Uniphase Netherlands B.V.

Durfee, Charles Colorado School of Mines

Gérard Mourou received a Doctorat Honoris Causa from the University of Quebec and the Institut National de Recherche Scientificique on November 28, 1999.

Gérard Mourou was the recipient of the 1999 David Sarnoff Award from IEEE.

Duncan Steel received the College of Engineering Service Excellence Award. He was also honored with being named the first Peter S. Fuss Professor of Engineering and received a Guggenheim Fellowship this year

Donald Umstadter received the Department of Nuclear Engineering and Radiological Science Outstanding Achievement Award.