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NIT >> Education >> Webcast Archive
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Nonlinear Optical Spectroscopy
Eric W. Van Stryland
Professor of Optics and
Director, School of Optics/CREOL
University of Central Florida, Orlando, Florida
Abstract
I will discuss experimental methods for characterizing the nonlinear absorptive and nonlinear refractive properties of materials from semiconductors to organics, e.g. transmission, Z-scan, femtosecond pump - white light continuum probe. This latter method allows the relatively rapid determination of the nondegenerate nonlinear absorption spectra from which nonlinear refraction may be determined via nonlinear Kramers-Kronig relations. These relations will also be discussed. I will end with a brief discussion of optical limiting.
Biography
Eric W. Van Stryland is Professor of Optics, Physics and Electrical and Computer Engineering in School of
Optics/CREOL, University of Central Florida. Eric Van Stryland received the Physics PhD degree in 1976, from the University of Arizona, Optical Sciences Center, Tucson, AZ, where he worked on optical coherent transients and photon counting statistics. He worked in the areas of femtosecond pulse production, multiphoton absorption in solids, and laser induced damage at the Center for Laser Studies at the University of Southern California. He joined the physics department at the University of North Texas in 1978 helping to form the Center for Applied Quantum Electronics. In l987 he joined the newly formed CREOL (Center for Research and Education in Optics and Lasers) at the University of Central Florida where he was Professor of Physics and Electrical and Computer Engineering. His current research interests are in the characterization of the nonlinear optical properties of materials and their temporal response as well as the applications of these nonlinear materials properties for sensor protection, switching, beam control etc. He helped develop the Z-scan technique with Mansoor
Sheik-Bahae with whom he also established the methodology for apply Kramers-Kronig relations to ultrafast nonlinearities. He is a fellow of the Optical Society of America, a former member of their Board of Directors and co-chair of the Science and Engineering Council, a senior member of the Laser Institute of America and a former board member, a senior member of IEEE LEOS and a member of the
SPIE, and MRS. He also served as a topical editor for Optics Letters. He has been Director of the School of
Optics/CREOL since July 1999.
In cooperation with
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archived webcast
October 3, 2003
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Quantum Cascade Lasers
Dr. Claire Gmachl
Lucent Technologies
Abstract
Semiconductor intersubband Quantum Cascade (QC) lasers are a new and rapidly evolving technology. Some of their strengths are the intrinsic mid infrared wavelength tailorability, high-speed modulation capabilities, and fascinating design potential. After a short introduction into the basics of QC-lasers and their applications, several recent aspects will be discussed. We will present a monolithic "supercontinuum" QC-laser. Cooperating, individual, but all-dissimilar intersubband optical transitions have been designed to provide broadband optical gain from 5 to 8 micrometers wavelength. Laser action with a Fabry-Perot spectrum covering all wavelengths from 6 to 8 micrometers simultaneously has been demonstrated. Lasers, which emit light over such an extremely wide wavelength range, are of interest for applications as varied as terabit optical data communications or ultra-precision metrology and spectroscopy. Another particular interest in QC-lasers concerns their high-speed modulation capabilities and potential application to free-space optical wireless systems. This is a recent addition to the more common and well-proven use of the lasers in mid-infrared trace gas sensors, such as environmental, automotive, or medical applications. Finally, there is considerable interest in extending the wavelength range of QC-lasers to the fiber optic wavelength. We will briefly discuss the potential of group III nitrides for short wavelength intersubband lasers and photonics devices based on intersubband transitions. Time permitting I will briefly discuss our recent work on non-linear generation of light in QC-lasers.
Biography
Claire Gmachl received the Ph.D. degree (sub auspicies praesidentis) in electrical engineering from the Technical
University of Vienna, Austria, in 1995. Her studies focused on integrated optical modulators and tunable
surface-emitting lasers. In 1996, she joined Bell Laboratories, Lucent Technologies, Murray Hill, NJ, as Post-Doctoral Member of Technical Staff to work on quantum cascade laser devices and microcavity lasers. She is currently a Distinguished Member of Technical Staff in the Semiconductor Physics Research Department, working on quantum cascade laser devices and applications and on intersubband photonic devices. Dr. Gmachl has co- authored over 120 publications in peer-reviewed journals, has given numerous invited talks, and holds 15 patents. She has been named a
Bell Labs Distinguished Member of Staff in 2002; she is a 2002/03 IEEE/LEOS Distinguished Lecturer and one of MIT's
"TR100" of 2002, she is also a co- recipient of the 2000 "NASA Group Achievement Award", and a recipient of the
1996 "Solid State Physics Award" of the Austrian Physical Society, and the "1995 Christian Doppler Award" for
engineering sciences including environmental sciences. She is senior member of IEEE LEOS, and a member of
numerous other professional societies.
In cooperation with IEEE Canada Toronto Section
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archived webcast
April 9, 2003
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There Are No Fundamental Limits to Optical Lithography
Professor Steven R. J. Brueck
Center for High Technology Materials
University of New Mexico
Abstract
Progress in optical lithography has paced the enormous progress in integrated
circuit technology. The ultimate possible limits of optical lithography are explored.
The spatial frequency transmission bandwidth of free-space is 2/l, leading to a
dense (equal line/space) pattern at a critical dimension of l/4 (or 50 nm for a l of 200 nm).
Immersion provides another factor of ~ 1.5 down to a ½ pitch of 33 nm at l ~ 200 nm.
Various strategies will be discussed for extending this capability to arbitrary patterns
rather than simple gratings. Nonlinear processes, based on the chemistry of photoresist
processing and pattern transfer, can further extend optics beyond the linear systems
limits of single exposures. The conclusion is that there is no fundamental limit to the
resolution of optical lithography; there are only process latitude and manufacturing
(e.g. cost) issues.
Nanotechnology is of great current interest. For many applications, large numbers of
nanostructures with a well-defined long-range order are required. One such example
is the use of nanostructuring for semiconductor materials development. Two examples
will be discussed as time allows: nanoheteroepitaxy (NHE) for the growth of highly
lattice mismatched systems (e.g. GaN on Si); and selective MBE growth of InAs
quantum dots on patterned GaAs substrates.
Biography
Dr. S.R.J.Brueck received a B.Sc. from Columbia University in 1965 and a
M.Sc./Ph.D. from MIT in 1967/1971. In 1971, he joined the Quantum Electronics
Group at MIT Lincoln Laboratory. In 1985 he became the director of the Center for
High Technology Materials (CHTM) and a professor of Electrical and Computer
Engineering and Physics at the University of New Mexico.
Dr. Brueck has made extensive experimental and theoretical research contributions
in many aspects of optics and laser spectroscopy. Material systems investigated include
semiconductors, molecular gases, simple molecular liquids, and plasmas used for
semiconductor processing. Under his direction, CHTM has become a well established,
internationally recognized center for optoelectronics and microelectronics research.
Dr. Brueck has published over 200 research articles. He has edited 7 books, been
awarded 21 patents and serves as an editor in many journals. He is a fellow of IEEE
and OSA and received the IEEE Third Millennium Award.
Nortel Institute for Telecommunications of the University of Toronto &
Edward S. Rogers Sr. Department of Electrical and Computer Engineering
Distinguished Lecture Series
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archived webcast
October 22, 2002
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Towards eHealth: the promise, perils and paradoxes of telecommunications in the health system
Dr. Alejandro (Alex) R. Jadad, M.D., D.Phil.
Director, Program in eHealth Innovation; Senior Scientist, Division of Clinical Decision-making and Health Care Research; Rose Family Chair in Supportive Care; Professor, Departments of Health Administration and Anaesthesia; University Health Network, University of Toronto
The health system provides unparalleled opportunities to understand and influence the role that technology plays in society.
Technology is promising opportunities for more rapid, more effective, and wider organization and exchange of health knowledge. Unlike any other era, massive amounts of information - both scientific and experiential - can now be exchanged in all directions: professional to professional, professional to public, public to professional, and public to public. Therefore, it is no longer the availability of information that determines the quality of decisions, but how the information is accessed, interpreted, exchanged, integrated and applied by all the interested parties.
The information age is also creating many new challenges and perils. Thinking that fancy technology and information will lead, on their own, to a richer, more efficient, balanced, humane and equitable health system-public relationship has proven naïve. The rapid developments in information technology are outpacing the ability of the system to keep up. Most health-related programs and health care systems were built for the pre-Internet era. The level of connectivity and compatibility of the computer systems across organizations that provide health services, and often among components of the same organization, is poor. Policy makers and managers are unable to monitor the impact of technology on health-related issues or to respond to the opportunities to improve health services created by new technology. Health professionals are feeling overwhelmed by clinical work and do not have the time or the incentives to re-tool and adapt their practices to the information age. Patients and other members of the public are using the Internet increasingly for health-related reasons, but many still do not have access to it. Those with access, however, find that the system is not adapting fast enough to meet their needs.
In this lecture, I will:
- Present data from studies that have evaluated the impact of technology on the public-health system relationship;
- Highlight the main lessons learnt from ongoing projects that explore, with input from patients and health care providers, the role of the Internet on the health system;
- Discuss how and why overcoming existing barriers that are hindering the full potential of technology will require substantial changes in the levels of health literacy of the general population, in the structure and politics of the health system and even in the way in which humans think and behave.
Biography:
Dr. Jadad is a 37-year old Colombian-born physician, patient advocate, researcher and educator. In 1994, he received a Doctor of Philosophy degree at the University of Oxford (Balliol College), becoming one of the first physicians in the world with a doctorate in knowledge synthesis. In 1995, he moved to Canada and joined the Department of Clinical Epidemiology & Biostatistics at McMaster University, where he was Professor and Chief of the Health Information Research Unit and Director of the McMaster Evidence-based Practice Centre. In October 2000, he moved to Toronto. His research focuses on the development and evaluation of unique strategies to enhance the health system, through state-of-the-art technology, to help people access and use the knowledge and services they require to meet their health-related needs, regardless of who or where they are. In 1997, Dr. Jadad received a National Health Research Scholars Award, from Health Canada; in 1998 one of ‘Canada’s Top 40 Under 40’ awards, and in 1999 a Premier’s Research Excellence Award, in recognition for his efforts to improve our understanding of the role of knowledge and technology in health-related decisions. Alex is married, with two children (and enjoys spending time with them more than anything else). He also likes to play the piano and perform close-up card tricks (all at a basic level).
Nortel Institute for Telecommunications of the University of Toronto &
Edward S. Rogers Sr. Department of Electrical and Computer Engineering
Distinguished Lecture Series
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archived
webcast
January 16, 2001
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Reconfigurable Multiple-Wavelength
Optical Systems and Networks
Dr. Alan Willner
Dept. of Electrical Engineering - Systems
University of Southern California
Three major thrusts will be discussed relating to the exciting area of wavelength-division-multiplexed (WDM) communications, a technique involving the simultaneous transmission of several channels on different wavelengths down the same fiber. The first part of the presentation will provide an overview of the revolution in optical communications caused by WDM and optical amplifiers. The second section is aimed at dynamically compensating channel-degrading effects in reconfigurable systems. These time-dependent degrading effects will occur since next-generation WDM systems will route signals through slowly-reconfigurable network paths, allowing several parameters to vary. Therefore, it is imperative to provide robust dynamic schemes for the compensation of issues such as unequal channel powers, EDFA transients, and chromatic and polarization-mode dispersion. The third thrust is aimed at enhancing the functionality of future packet-switched optical networks, in which each WDM packet can be actively routed through a network based on wavelength and packet information. Significant functions that can be enabled by high-speed optical switches include: contention resolution, header replacement, and synchronization.
In cooperation with
IEEE LEOS
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May 29, 2000
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