The Center for Ultrafast Optical Science (CUOS) is an interdisciplinary research center in the College of Engineering at the University of Michigan in Ann Arbor. CUOS was sponsored as a Science and Technology Centers by the National Science Foundation during 1990-2001. Its mission is to perform multidisciplinary research in the basic science and technological applications of ultrashort laser pulses, to educate students from a wide variety of backgrounds in the field, and to spur the development of new technologies.

CUOS researchers develop optical instrumentation and techniques to generate, manipulate, and detect ultrashort and ultrahigh-peak-power light pulses. They use these ultrashort pulses to study ultrafast physical phenomena in atomic, nuclear, plasma, and materials physics, in solid-state electronics, in high-energy-density physics, and in biomedicine.

Ultrafast science & technology is one of the most exciting fields in science and engineering today. Ultrashort laser pulses are the shortest controlled bursts of energy ever developed. Optical pulses of a few femtoseconds (10^-15 seconds) duration can be used to probe the fastest events in atomic, molecular, biochemical, and solid state systems. When amplified to even modest energies, such short pulses can achieve the highest peak powers: the Hercules laser at CUOS holds the world record for on-target laser intensity, at an astonishing 10²² watts per square centimeter. Ultrashort-pulse fiber lasers enable the highest average powers (100-Watt level) available from pulsed laser systems.

Because of these unique properties of ultrashort laser pulses, the field of ultrafast science and technology encompasses a wide range of applications beyond optics and lasers. Optical communications at the terabit level requires pulses in the few-hundred-femtosecond range.High speed electronics and optoelectronics in the terahertz (THz) regime are accessible with femtosecond lasers. The behavior of electrons in quantum structures such as quantum dots, quantum cascade lasers, and nanomaterials may be directly studied. Materials science with nanometer-precision micromachining exploits ultrafast pulses at moderate intensity. Biomedical applications include eye surgery (for example the Intralase process), subcellular “nanomachining,” and invivo sensing (for example in vivo cytometry of circulating cancer cells). At ultrahigh intensity (multi-terawatt peak power), research  frontiers include physics with relativistic plasmas, accelerator beam physics, nuclear physics, high-energy physics, astrophysics, cosmology, and medical applications such as hadron therapy.

CUOS under the joint sponsorship of NSF, UM, CoE and the State of Michigan has been one of the pioneers of this ultrafast optics revolution. For nearly twenty years, CUOS has been a unique and well-recognized incubator for multidisciplinary research. In addition to its research, it has had a major impact on education: more than 150 Ph.D. students have been trained in CUOS laboratories. In addition, CUOS has contributed to developing industries based on its discoveries and inventions. Five companies have been spun off, with four started by former CUOS scientists: Picometrix (fast detectors, S. Williamson and J. Valmanis), Clark-MXR (scientific lasers and micromachining, P. Bado), Translume (waveguide optics, P. Bado) and Intralase(precision surgery, R. Kurtz and T. Juhasz). Most recently Arbor Photonics was founded by CUOS Prof. Almantas Galvanauskas to develop high power fiber laser technology. CUOS has also attracted companies to Ann Arbor such as IMRA-America which has become a leading company in short-pulse fiber lasers. These companies have created numerous high level jobs and developed an ultrafast-optics-based industry with Ann Arbor as its hub. This new industry attracts outstanding scientists to Ann Arbor and benefits from the high-quality students trained at CUOS. The companies have attracted more than $10M over the past ten years in SBIR (Small Business Innovation Research) and STTR Programs.

In 2002 CUOS was helpful in attracting one of the NSF Physics Frontier Centers to the University of Michigan – FOCUS (Frontiers in Optical Coherent and Ultrafast Science). As a part of FOCUS, CUOS has built a 300 TWs laser HERCULES. This system has demonstrated the highest intensity ever focused on target and is used to study the fundamental properties of relativistic plasma it produces and for the development of high-energy table top sources of radiation such as electrons, ions, positrons, gamma-rays, x-rays, neutrons, etc. 

In 2004, CUOS added lab space in the newly-built Gerstacker Building which houses the Department of Biomedical Engineering and research space for the Department of Materials Science & Engineering. The addition of these departments next to CUOS is greatly helping to facilitate growing interdisciplinary research efforts in optics, imaging, nanotechnology, biomaterials, and tissue engineering. Faculty from many departments within the College (EECS; Nuclear Engineering and Radiological Sciences; Atmospheric, Oceanic and Space Sciences; Materials Science and Engineering; Biomedical Engineering, and Chemical Engineering). CUOS also maintains vigorous interactions with other University Centers, the Michigan Nanofabrication Facility, and the Michigan Nanotechnology Institute for Medicine and Biological Sciences (M-NIMBS).

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 one of the most significant early contributions of CUOS was the invention and development of high-repetition-rate Ti:sapphire amplifiers based on chirped-pulse amplification (CPA). Both the millijoule, kilohertz-repetition-rate class amplifiers and the microjoule, 250-kHz-repetition-rate systems that are now found in nearly every major ultrafast optics lab worldwide were first pioneered at CUOS. With white light continuum generation and ultrafast parametric amplifiers, femtosecond pulses can be readily produced across the visible and near-infrared spectrum, enabling researchers to study “electron-volt” physics and chemistry. For example, a continuing theme of CUOS research has been the study of ultrafast processes in semiconductors and optoelectronic devices, such as quantum dots, semiconductor lasers, and high-mobility quantum transport structures. The generation and applications of terahertz (THz) radiation is also enabled by ultrafast lasers, opening up imaging and spectroscopy in the far-infrared region of the spectrum.

A major thrust of CUOS has been and continues to be the development of CPA systems to achieve the highest possible peak power. This has led to the establishment of “high field science” – the fundamental interaction of light at extreme intensities with matter – where the relevant electron energies are kilo-electron-volts to even giga (billion) electron volts. The impact of our CPA development on both peak intensity and average power is illustrated in Figure. 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 education and technology transfer. The environment of the Center is stimulating and challenging for both undergraduate and graduate students. The Center places a high priority on transferring technology into the marketplace. CUOS pursues active collaborations with companies through SBIR and STTR programs, as well as through informal exploratory collaborations. Several companies have spun off from the Center, and numerous patents and licensing arrangements provide a further avenue for technology transfer.

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:

• High-Field Science is based on the creation of extremely high peak-power levels by squeezing pulses with modest energy levels into ultrashort time frames. When focused, these pulses create electric field strengths far exceeding those that bind the inner-most electrons of an atom to its nucleus, and electron motion becomes relativistic. The fundamental physics of laser-plasma interactions at these extreme intensities and their applications to particle acceleration and short-wavelength generation are the main themes.
• Ultrafast and High Power Fiber Lasers concerns the fundamental aspects of ultrashort pulse generation and amplification in fiber lasers.
• Ultrafast Science applies ultrashort-pulse lasers to the study of high-speed dynamics, with a focus primarily on condensed matter systems of importance to emerging electronic and optoelectronic technology.
• Terahertz Optoelectronics refers to the development of novel single- or few-cycle far-infrared (mm or sub-mm wave) radiation. Applications include sensing, spectroscopy, and imaging.
• Ultrafast Biomedical Optics concerns the application of femtosecond lasers to biomedical problems. These include highly controlled laser ablation, enabling sub-cellular manipulation (“surgery”), fabrication of nanoscale channels for “nanofluidics,” the use of multiphoton excitation for in vivo sensing (e.g. in vivo flow cytometry), coherent control for selective imaging, etc.
• Materials Science concerns micromachining, nanomorphing (generation of nanoscale structure in a controlled way), laser-induced breakdown spectroscopy, and materials characterization with ultrafast x-rays.

The mission of the Center is to investigate that fundamental science and applied technology which “pushes the envelope” of ultrafast optics. The field is intrinsically interdisciplinary, as it involves coupling state-of-the-art laser optics with applications in far-flung fields which often have no apparent (or prior) connection to optical science. By following the links under “research,” you will find general overviews of the areas of research active at CUOS in each of these areas, as well as more detailed information representative of specific programs.

Graduate Education
The Center’s most important educational role is the training of graduate students, skilled in interdisciplinary research, who will be highly sought after by industry and academia. CUOS provides a unique interdisciplinary research training environment, in which students from a wide variety of backgrounds work together on projects applying state of the art femtosecond laser technology to problems in basic science and technology in other fields (examples are materials science, biomedical engineering, nuclear engineering and plasma physics, semiconductor electronics, and imaging). CUOS has trained well over 100 PhD’s in ultrafast science and technology, and approximately twenty students are engaged in research in CUOS labs at the present time. CUOS students often participate or collaborate with other University of Michigan research centers, such as FOCUS, MNF, and M-NIMBS.

Technology Transfer
The Center has consistently participated in active industrial collaboration ever since its creation. Translation of ultrafast optical technology into the commercial sector has been and continues to be a high priority for CUOS. Industrial interactions take several forms, as described below. Collaborations using CUOS facilities. CUOS faculty and staff actively seek collaborative research with industry. Ultrafast lasers with a wide range of operating parameters (wavelength, pulse energy and duration, and average power) are available at CUOS for collaborative work. Working relationships may range from simple informal exploratory collaborations to contractually binding agreements. Laboratory time may be made available for specific periods of time, to explore solutions to problems or test new products. When work that is performed at CUOS is of proprietary interest to individual associates, appropriate contractual agreements are made to safeguard these interests. In many cases, joint publication of scholarly work results from the interaction. It is explicitly understood that 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 CUOS 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. Parties interested in collaborative research should contact the CUOS Director, who will identify potentially interested CUOS personnel.

Industrial research using CUOS facilities on a recharge basis. As above, CUOS laser facilities may be made available for industrial research on a recharge basis, subject to availability. Interested people should contact the Director.

SBIR/STTR programs. CUOS has participated and continues to participate in numerous SBIR and STTR collaborations. These have proved a very effective means of developing new commercial applications of ultrafast optical technology. Present STTR activity includes collaborations with Picometrix on THz generation and imaging.

Spin-offs. CUOS has an established record of generating spin-off companies. Five companies have their origins in the Center, with four started by former CUOS scientists: Picometrix (fast detectors and THz instrumentation, S. Williamson and J. Valmanis), Clark-MXR (scientific lasers and micromachining, P. Bado), Translume (waveguide optics, P. Bado) and Intralase (precision surgery, R. Kurtz and T. Juhasz). Most recently Arbor Photonics was founded by CUOS Prof. Almantas Galvanauskas to develop high power fiber laser technology.

Patent and licensing activity. Patents are key to technology transfer both to startups and to established companies. 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. An example of the process is provided by Intralase, based in Irvine, CA. The application of femtosecond lasers to corneal surgery was developed at CUOS, and Intralase was formed to commercialize the process under patents developed at CUOS through TMO. Intralase was granted FDA approval for its Femtosecond Laser Keratome System in January 2000, and the company has seen rapid growth based on the extraordinary success of the procedure.

Ultrafast science is the study and subsequent implementation of physical phenomena that occur at the shortest time scales known in science, from picoseconds to femtoseconds to attoseconds. Snapshots in this time domain reveal the most fundamental mechanisms of molecular, atomic, and electron interactions. Ultrafast science enables us to answer such questions as how molecules move in liquids or gases, how electrons collide in semiconductors and superconductors, and how light initiates the vision process.

The Center for Ultrafast Optical Science (CUOS) at the University of Michigan was chartered to advance the scientific and technological applications of ultrashort optical pulses. The heart of the Center is its unique combination of state-of-the-art short-pulse and high-intensity lasers, capable of generating peak powers up to 300 trillion Watts. Their operating principle, Chirped-Pulse Amplification (CPA), was developed by CUOS scientists. The tremendous peak power, generated by a laser which rests on a single table-top, is contained in bursts of laser light that are less than 100 femtoseconds in duration. That’s only .0000000000001 seconds, or far less time that it takes for light to travel the thickness of a sheet of paper. A supersonic aircraft travels less than the diameter of an atom in this time!

Ultrafast is Ultrashort. These unique lasers enable us to examine and to understand phenomena that occur on “ultrashort” time scales. For example, these lasers can freeze the motion of atoms in a vibrating molecule. They can even resolve the rapid tiny motion of electrons within a single atom, which form the foundation of quantum chemistry and physics. Powerful ultrashort light pulses can modify surfaces in new ways. This may lead to new materials, and new opto-electronic devices which operate at unprecedented speeds. CUOS has also developed techniques to sculpt these short laser pulses, to alter their color and amplitude to high precision. The shaped pulses of light are tools that can be used to engineer new quantum structures in atoms and molecules. The ultimate aim is to control atomic and molecular processes in gases, liquids, and plasmas for purposes ranging from materials processing to light-source production to particle acceleration.

Ultrafast is Ultra-precise. Short bursts of energetic laser light have many surprising properties that can lead to a variety of novel applications. For instance, materials which are normally optically transparent become opaque. Thus, micro-machining or incisions can be made beneath the surface of some materials, without damaging the surface of the medium. This concept of “ultra-precise” materials processing led researchers at the Center to consider using ultrafast lasers as surgical tools. Specifically, CUOS scientists are working on Ophthalmologic applications. Various types of eye surgery may be significantly improved by replacing the traditional scalpel or laser, with an ultrafast laser. Researchers have already demonstrated that the quality of an incision made by an ultrafast laser is greater than those produced by conventional lasers. New surgical techniques which are only possible using ultrafast lasers are presently under investigation. This research may lead to significantly improved eye care — surgery that once had to be performed in an operating room, could now place in a doctor’s office. Not only can these lasers cut, but they are powerful imaging tools as well. At least three different areas of microscopy are presently pursued at the Center. These microscopes can be used to image and examine important biological systems or materials, or to study the path of electrical current through microchips operating at high speeds.

Ultrafast is Ultra-broad.  X-rays have revolutionized medicine, science and technology. Bright, coherent ultrashort flashes of X-rays can take movies of proteins, pathogens and nanostructures, giving insight into their workings. Despite the demand, only a few dedicated Synchrotron facilities exit worldwide, partially due the size and cost of conventional accelerator and wiggler technology. Here, at CUOS we have shown  that X-rays of a quality similar to 3rd generation Synchrotrons can be obtained in a university scale laboratory, on a spatial scale of millimeters rather than tens of meters of conventional light sources, using a 100 Terawatt laser focused into a gas. This scheme has recently demonstrated high quality beams of electrons.  The generated plasma wave that accelerates the electrons can also wiggle them. Operating in the non-linear regime, this yields a high quality X-ray beam, which is spatially coherent, emanates from a micron-sized source, has 10-100 keV photon energy, milliradian divergence, ten femtosecond duration and a peak brightness of up to 10²² ph/s/mrad²/mm²/0.1%BW, which is comparable to 3rd generation Synchrotrons. The measured radiation is spatially coherent, opening up a multitude of applications, such as phase contrast and lensless imaging, previously only possible with large conventional light sources. The concept of the laser plasma wiggler has the potential of making novel radiation sources more compact, economical and abundant, and thus impacting progress all across science and technology.

Ultrafast is Ultra-intense. Chirped-Pulse Amplification is a method for producing lasers of unprecedented intensity. Our most intense  laser produces pulses which exceed 300 Terawatts (300 trillion Watts). During its short duration, the power in each pulse exceeds the total power generated in the United States by 300 times. The light can be focused to 2×10²² watts per square centimeter (2 with 22 zeroes or 20000 billion Watts per square centimeter), which considerably exceeds the intensity of any other radiation source on earth. These are sources for studying fundamental physics in a new regime. Beyond that, there are important technological benefits to these new light sources. CUOS scientists are studying advanced problems such as compact accelerators, broad-band light sources, and nonlinear plasma channeling effects.