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Scientific & Technological Research

Femtosecond optical pulses are the shortest controlled bursts of energy yet produced, and enable the highest laboratory peak-power densities ever generated. These two characteristics have opened up access to a number of new fields of research not previously available to basic science and applied technology. In the original establishment of the Center, it was pointed out that "ultrafast optical science is an inherently interdisciplinary effort ... [requiring] the collaboration of scientists and technologists working on laser and optical physics, atomic and condensed-matter physics, chemistry, optical fibers, and electronics. The field requires all of their efforts and, in turn, rewards each with otherwise unattainable opportunities of discovery in their own fields." The remarkable growth and success of CUOS has amply demonstrated the truth of that statement. The Center now includes researchers in all of those fields, as well as in plasma physics, accelerator physics, materials science, biophysics, and medicine, all working closely with scientists developing new ultrafast laser sources and measurement techniques - in short, in a "center mode" of research.

The inception of the Center coincided with the rapid development of mode-locked solid-state lasers, and much of the focus was originally on "electron-volt physics," easily observable with visible-wavelength photons, such as electronic dynamics in condensed matter. The further development of chirped pulse amplifiers (CPA) at CUOS has resulted in major improvements in our ability to do electron-volt physics and chemistry. Most spectacularly, it has also given rise to an explosion in "high-field" science and technology, in which the relevant electron energies are kilo-electron-volts to even tens of million electron volts. The impact of our CPA development on both peak intensity and average power is illustrated in Figure 1. High-field laser interactions with plasmas have opened up a world of possibilities in short-wavelength generation, so that now ultrashort pulses are available from the terahertz to the exahertz region of the spectrum.

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

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

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

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

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

In high-field science, CUOS participants have made significant contributions to high-field atomic physics, laser-plasma interactions, optical breakdown, short-wavelength generation, and electron acceleration. This has been enabled by the availability of both state-of-the-art lasers, combining high-intensity with ultrashort pulse duration, and the requisite expertise to apply them. For instance, CUOS research in both impact ionization and femtosecond lasers providing intensities at the 1014 W/cm2 level have led directly to breakthroughs in the understanding of optical breakdown of materials, and thus to the development of applications in micro-machining and laser surgery. Technology transfer efforts have been able to focus on commercializing these applications. Developing expertise in plasma, atomic, and optical physics has also led to new advances in uv and xuv sources. In the coming five years, new laser sources (especially sub-10-fs lasers) and high-intensity terahertz pulses will allow new investigations in the areas, optical breakdown mechanisms, atomic physics, and uv and xuv generation.

The development at the Center of lasers capable of generating focused intensities of greater than 1018 W/cm2 has provided access to a new physics regime, as a consequence of the relativistic motion of electrons in the laser field. This has lead to the first observations of relativistic nonlinear optics and of wake-field acceleration of electrons. Investigations of high-field physics have enabled a major Center focus on laser wake-field acceleration of electronics. Indeed, its recent demonstration at CUOS might be considered the culmination of a broad program in ultrafast laser development and high-field laser-matter interactions, and thus will form a major continuing thrust over the coming years. The next generation of ultrahigh-power lasers will make possible a research program in several exciting areas. At the highest intensities (1019 - 1020 W/cm2), entirely new nonlinear optical phenomena are expected, having applications in a broad area of science and technology, including astrophysics and novel fusion concepts, as well as compact and ultrafast x-ray and electron sources.

Due to the intrinsically interdisciplinary nature of the work described, it is found to be ideally suited to a center mode environment. Special attention therefore continues to be focused on those areas that will particularly benefit from collaborative, innovative, center-style research. A strong track record of breaking ground in new fields of basic science, of transferring successful technologies to the commercial sector, and of providing students with an unparalleled environment for multidisciplinary education and research, is the hallmark by which the Center will continue to attempt distinguishing itself.

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Visiting Fellow Program

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

Sabbatical visitors are typically on one-year research leave from their home universities. They are given visiting professor status in physics, chemistry, or engineering, and they have offices and share laboratory space in the Center. The position of Center Fellow is patterned after the Michigan Society of Fellows. These are typically appointments of 1-3 years that are provided to young independent scientists. We have already had more than a dozen Center Fellows in physics, electrical engineering, and ophthalmology (a shared appointment with U-M's Kellogg Eye Center). Several have gone on to faculty positions or jobs at national laboratories or in industry.

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

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Graduate Education

The Center's most important educational role is the training of graduate students, skilled in interdisciplinary research, wand who will be highly sought after by industry and academia. A stated goal is to train an every-increasing number of minority and female graduate students who will become the faculty of the future.

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

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

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K-12 and Community Outreach

As an NSF Science and Technology Center, CUOS defines one of its goals to work at broadening the pool of future scientists and engineers. This is especially true in regard to including a more diverse cross-section of the American population. K-12 outreach is a natural part of this effort, since it is often too little and too late trying to recruit under-represented minorities at the graduate or undergraduate level. A long-range perspective requires that we improve science and math education at all grade levels, while exposing children and teens to career exploration activities that can motivate them to pursue the educational foundation necessary for technical careers.

Over the years, CUOS has learned that an effective way to make fundamental and systemic changes in education if to involve everyone with a stake in it: students and parent, teachers and administrators, business and community organizations, and colleges and universities. We realize that assisting youngsters with their learning is a labor-intensive endeavor and requires a long-term commitment to building relationships among all of those involved. Given the fact that CUOS faculty and students are engaged full-time in research, K-12 outreach efforts cannot take up a great deal of their time and lives. A way to have significant impact however is by linking the efforts of many people and organizations. Accordingly, CUOS' K-12 Outreach Office helped form, in the fall of 1995, the Southeastern Michigan Math-Science Learning Coalition, involving partners from K-12 education, parent groups, government, higher education, business, and community groups that included museums, youth center, 4-H Extension, and other non-profit education groups. Our vision is to link and connect people and resources with educators, children, and parent so that youngsters may receive help learning math and science and may enjoy a wide variety of experiences to explore career interests. To date, some 65 previously disparate individuals and groups have come together to build a critical mass, resulting in an explosion of creativity and cooperation. Within the University of Michigan, and just through word-of-mouth, 28 departments, museums, and centers have stepped forward to join efforts.  As a university-based organization, CUOS has been able to develop and offer to others a World Wide Web site to manage and communicate partners' resources, located at www.eecs.umich.edu/mathscience.

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Knowledge Transfer

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

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

The Center has established a program whereby industrial associates may participate in on-site laboratory activities through the Center's Ultrafast Development Laboratory (UDL), which makes laboratory space available for specific periods of time, so that they can explore solutions to problems or test new products. When work that is performed under the UDL program is or proprietary interest to individual associate members, appropriate contractual agreements are made to safeguard these interests. UDL operates with the full intellectual support of the Center's faculty and staff. In many cases, joint publication of scholarly work result from the interaction. It is explicitly understood that the corporate associates will move developing ultrafast technology into their commercial product and process lines. The university's interest, if any, is represented through published works and agreements that are executed through it Technology Management Office and/or its Division of Research and Development Administration. Industrial participation in the UDL is predicated on a balanced contribution of financial and in-kind support. This typically consists of a combination of cash, professional labor time in collaborative research or student mentoring, and equipment loans or donations. University sub-contracting in Small Business Innovation Research (SBIR) and Small Business Technology Transfer Research (STTR) projects is also encouraged. Specific programs and relationships are reviewed on a yearly basis; multiyear programs are not unusual. Working relationships may range from simple collaborations to contractually binding agreements.

The ability to provide stability to spin-off companies is often tied to their having access to certain product patent rights. The Center has had a continuous flow of patents that are applied for through U-M's Technology Management Office (TMO).  From this group of patents, licenses have been sold and others are under negotiation. A new spin-off business, involving the application of femtosecond lasers in ophthalmology, has developed into the company IntraLase which is based in Irvine, CA and was granted FDA approval for its Femtosecond Laser Keratome System in January 2000. Research is continuing, in collaboration with U-M's Kellogg Eye Center (KEC), to capitalize on the considerable benefits associated with ultrafast laser pulses in precise ophthalmological surgery. A coalition of scientists from KEC and CUOS has been exploring possible treatments of glaucoma and cataracts, and procedures for retinal surgery. Discussions are proceeding with commercial firms to establish business liaisons and strategic plans for launching a spin-off business to make use of the techniques being developed, as well as the compact lasers being designed and built as part of the program.

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For additional information, contact the following individuals:
Director: Gerard Mourou
Fellows Program: Philip Bucksbaum
Industry Liaison: Peter Pronko
Educational Outreach: Herbert Winful & Jeannine LaSovage
Ultrafast Optics: John Nees
Ultrafast Science: Ted Norris
Ultrafast Technology: John Whitaker
High-Field Science: Donald Umstadter
High-Field Technology: Gerard Mourou


General Info / CUOS Activities