Colloquium

Fall 2004

December 2, 2004 -- Optical Sciences Colloquium -- 3:45 p.m. -- Meinel 410
George C. Valley of the Areospace Corporation's Electronics and Photonics Laboratory will present Photonic Analog-to-Digital Converters: Fundamental and Practical Limits.  Abstract:  This talk presents the fundamental and practical limits on the performance of photonic analog-to-digital converters (ADCs).  First, we review the classes of photonic ADCs that have been investigated to date.  Then reported performance of these ADCs is compared to performance recently obtained with high rate, high resolution electronic ADCs.  Next, the paper concentrates on the optical sampling/demultiplexing class of photonic ADCs and derives the fundamental limits that are determined by amplitude noise, timing jitter and the finite width of the optical sampling pulse.  Then, we review practical limits for the demultiplexing or time-interleaved photonic ADC.  These practical limits are generally determined by the performance of the electronic-to-optical and optical-to-electronic interfaces, the optical modulator and the photodetector, and by the requirements on path and component matching.  Finally, the analysis is extended to four other types of photonic ADCs: Nyquist-rate, oversampling or delta-sigma, laser-strobed and time-stretched ADCs.

December 1, 2004 -- Optics Valley Lecture Series -- 5:15 p.m. -- Steward Observatory N210
Michael Bass will present Five Experiments that Define Modern Optics.  For more information, please visit the Optics Valley Web site at http://www.opticsvalley.arizona.edu

November 18, 2004 -- Optical Sciences Colloquium -- 3:45 p.m. -- Meinel 410
Daniel Malacara will present Optical Design and Testing in the Past Forty Years.  Abstract:  A description of the history and development of the optical design and testing during the past forty years with the most important developments and with a description of new trends will be described.

November 5, 2004 -- TSOSA's OSC Community Speakers -- Noon -- Meinel 410
(1)  Ranjan Grover will present Novel Devices for Chemical Sensing and Their Characterization Using Kelvin Probe Force Microscopy.  Abstract:  A common technique for achieving chemical sensing of very small gas concentrations is to use chemically-sensitive field-effect transistors (ChemFETs), solid-state sensors that have a chemically sensitive monolayer as a critical ingredient. The research in our group, enables characterization of the spatial nature of the chemical reaction of the gas with the chemically sensitive monolayer at a nanometer level, and also studies its temporal evolution. This research is essential in developing and deploying ChemFETs commercially.  (2)  Jason Auxier will present Applications of Glass Doped with Quantum Dots.  Abstract:  Quantum-dot doped glasses have several advantages over their epitaxially-grown counterparts: less expensive, more robust, more variation of concentration, and semi-uniform distribution throughout the material.  For photonics applications, a major advantage to glass is the ability to produce very low-loss waveguides.  In this presentation, I will review of the general optical properties of quantum dots and present previous results on laser mode-locking, optical gain, and luminescence.  Then, I will present data on the lowest-loss ion-exchanged waveguides in quantum-dot doped glass.  Measurements of loss, mode profile, and refractive index profile will be presented.  In addition, I will show optical measurements that demonstrate the quantum dots preservation throughout the waveguide production process.  I will conclude my presentation with a discussion of current work and some ideas for the future.

November 4, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
OSC alumnus Dr. Richard Buchroeder (PhD 1976) will present Adventures in Optical Design.  He will describe many of the quaint and curious designs he has done over the years and will talk about what life is like these days for an optical designer.

October 28, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Dr. David A.B. Miller, the W.M. Keck Professor of Electrical Engineering at Stanford University and the Director of the Ginzton and Solid State and Photonics Laboratories will present Optics Inside Computers.  Abstract:  As silicon CMOS clock speeds increase, and the amount of information that must be handled inside computing and switching machines increases, optical interconnection is increasingly attractive. For example, the need for very high densities of interconnects off of backplanes and boards drives the use of optics at shorter distances inside large machines. A key question is whether and how optics might be used down to the level of chips themselves. Many of the reasons for the use of optics at short distances, or to chips, will likely be different from those at long distances. Optics may be important both for interconnects and for synchronization. The talk will discuss these various areas and the work of our group, including recent work on sub-picosecond clock injection, wavelength division multiplexed interconnects, novel modulators, wavelength converter arrays, and nanophotonic wavelength spliitters, and future directions for combining CMOS and photonics inside machines.

October 22, 2004 -- TSOSA's OSC Community Speakers -- Noon -- Meinel 410
(1)  OSC PhD candidate Thomas Stalcup will present Atmospheric Tomography using Dynamically Refocused Rayleigh Beacons.  Abstract:  The resolution of large ground-based telescopes is severely limited by atmospheric turbulence.  This can be compensated for by sensing the errors introduced in the atmosphere and using a deformable mirror to correct these errors.  The first adaptive optical systems have used natural stars as a reference source to measure the atmosphere, but these systems are capable of looking at only 3-5% of the sky.  Using a projected laser beam instead of a natural star promises all sky coverage.  Recent testing has been done at the MMT on a system using relatively inexpensive lasers to produce a three dimensional measurement of the turbulence, something that no other group in the world has done.
(2)  OSC PhD candidate and Graduate Teaching Assistant Abdeq Abdi will present  Overview of Smart Structures and Infrastructure Optics.  Abstract:  An overview of infrastructure health monitoring systems is given through the concept of Smart Structures and Infrastructure Optics. A simulated application will be described using a 2 meter cantilever beam with a structurally integrated Fiber Bragg Grating Array utilizing Optical Frequency Domain Reflectometry as a demodulation scheme.

October 21, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Professor Masud Mansuripur of the University of Arizona Optical Sciences Center will present Radiation Pressure and the Linear Momentum of the Electromagnetic Field.  Abstract:  Johannes Kepler was the first to suggest that radiation pressure was responsible for the comets’ tails pointing away from the Sun. Newton also conjectured that light would exert pressure on material bodies and Bartoli deduced the existence of light pressure from thermodynamic considerations. In 1871, Maxwell used his new electromagnetic theory to quantify the strength of the radiation pressure. Maxwell’s predictions were verified by the experiments of Lebedev (1900) and Nichols and Hull (1901). The feeble pressure was detected by allowing the radiation to fall upon a delicately poised vane of reflective metal.  In free space a photon of wavelength λ carries a momentum p=h/λ, where h is Planck's constant. Thus when an atom emits or absorbs a photon its momentum changes in accordance with Newton's laws of motion. Similarly, when reflection or refraction from a particle changes the direction of a light beam, the particle experiences a force. The first optical traps employing these principles were built in 1970 by Ashkin. Levitation traps used the upward-pointing radiation pressure to balance the pull of gravity, whereas two-beam traps relied on counter-propagating beams to trap particles. In 1986, Ashkin and coworkers used a single, tightly focused laser beam to trap a transparent particle in three dimensions. Such “optical tweezers” are particularly useful when working with biological samples because conventional manipulators can contaminate the sample. In conjunction with microfluidic devices, optical tweezers are now used routinely to manipulate biological and other samples, and also to drive/control micro-pumps, micro-valves and micro-reservoirs.  In this presentation we describe a new theoretical model for computing the force of the electromagnetic radiation on material objects. Among other predictions, the new model reveals the existence of a lateral radiation pressure inside dielectric media, exerted at and around the edges of a finite-diameter light beam. Contrary to current belief, the lateral pressure turns out to be compressive for s-polarized and expansive for p-polarized light. We also show that the optical momentum density inside dielectric media has equal contributions from the traditional Minkowski and Abraham expressions. Our model, used in conjunction with 3D Maxwell solvers, yields the distribution of fields and forces in diverse systems of practical interest.

October 18, 2004 -- Special Presentation -- 3:00 p.m. -- Mathematics 402
Professor Emeritus B. Roy Frieden of the Optical Sciences Center will present Physics from Information at a meeting of the University of Arizona student chapter of SIAM, the Society for Industrial and Applied Mathematics.  Abstract:  It has been known since Bohr and Heisenberg that the observer plays a key role in defining the laws of physics he/she experiences. For example, a photon behaves like a particle or like a wave depending on how it is observed. John Wheeler in 1992 proposed that the universe is "participatory," with the physical laws formed during an interchange of information during observation. This proposes that the laws can be derived out of information considerations. We have found that Fisher information, in particular, does the trick. In a nutshell, the laws arise out of a variational principle I - J = extremum where J is the information level intrinsic to the source effect and I is the information in a transform space accessible to the observer. We report on the details of the approach, which defines the laws of physics, biology, chemistry and even econophysics. The general reference is B.R. Frieden, Physics from Fisher Information (1998) or Science from Fisher Information (2004), both put out by Cambridge University Press.

October 14, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Dr. S. Pau of Bell Laboratories, Lucent Technologies will present Optical Subassembly and Nanotechnology.  Abstract:  Growth in Internet traffic has transformed the Optical Transport Network (OTN). The new generation of networks requires ability to provision, protect, restore and reconfigure multiple channels of optical signals in real time. New functionalities such as signal switching and filtering in the optical domain require new class of low cost, scalable and reliable optical subsystems. In the first part of my talk, I will present progress on the MEMS based 3D optical cross-connect (OXM), optical wavelength add/drop multiplexer (OADM) that are invented, developed and manufactured at Lucent Technologies.  Nanotechnology promises an unprecedented era of innovation across multiple disciplines and diverse applications. Its pursuits and activities are proliferating with different approaches, from top-down to bottom-up, and with varying maturity, from concept to commercialization. In the second part of my talk, I will present my recent research on various nano-fabricated devices, which utilizes top-down fabrication technologies. Specifically, results in miniaturized ion traps, chemical reactor and sensor will be presented. Applications include mass spectrometry, quantum computer and fuel cell.

October 7, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Dr. Wibool Piyawattanametha of the University of California at Los Angeles Department of Electrical Engineering will present Surface and Bulk Micromachined Two Dimensional Angular Vertical Comb Actuators Scanner for Endoscopic Ultrahigh Resolution Optical Coherence Tomography Imaging.  Abstract:   The Optical Coherence Tomography (OCT) has become a powerful method for imaging the internal structure of biological systems and tissues since its introduction in the early 1990s.  OCT is an optical imaging technique that is analogous to B-mode medical ultrasound except that it uses low coherent light (low coherence interferometry) to produce cross-sectional images instead of sound. The technology promises to have applications in a wide range of clinical situations:  imaging tissue pathology when excisional biopsy is hazardous or impossible, guiding surgical procedures, and reducing sampling errors associated with excisional biopsy.  Micro-electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology. The micromechanical components are fabricated using compatible "micromachining" processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices.  The recent growth of MEMS technology offers a revolutionary approach to implement compact, robust, light weight, high imaging resolution, and batch production of endoscopic OCT (EOCT) in vivo imaging systems.  The research work was focused on the integration of the two aforementioned technologies. The presentation will describe the design, fabrication, packaging, and imaging demonstration of surface and bulk micromachined two-dimensional (2D) angular vertical comb (AVC) actuators scanner for EOCT in vivo imaging systems.

September 30, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Dr. Serguei Stepanov of the Centro de Investigación Científica de Educación Superior de Ensenada Department of Optics will present Wave Mixing via Spatial Hole Burning in Er-Doped Fibers.  Abstract:  Dynamic gratings in Er-doped optical fibers are recorded via effect of “spatial hole burning” (i.e. local optical saturation of the fiber absorption or gain) with characteristic formation time of some milliseconds for typical cw recording power of some mW. They are considered to be responsible for instability of a single-frequency operation of fiber lasers, but can also be used to stabilize it. In addition to earlier demonstrated tunable narrow-band filters these gratings seem to be also very attractive for adaptive interferometry applications (i.e. in laser vibrometry, laser induced ultrasound detection etc.) since allow realization of an all-fiber adaptive interferometers. Experimental results on two-wave mixing via dynamic gratings in Er-doped fibers are presented and, in particular, grating anisotropic properties (associated with “polarization hole burning”) and possible physical mechanisms (resonance excitation transfer, upconversion processes etc.), which can reduce the grating amplitude, are discussed.

September 23, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Dr. Chuan Pu of the Center for Optical Technologies at Lehigh University will present MEMS and Micro-Optical Systems: Technologies and Applications.  Abstract: For the past decades tremendous advancement has been made on the integration of MEMS (Micro-Electro-Mechanical Systems) technologies and micro-optics. This integration has led to system miniaturization and innovative functionalities that enable many new applications ranging from consumer market products to instruments for exploratory scientific researches. This talk will present the fundamental optical MEMS technologies and their applications in bio-medical sensing, miniaturized optical imaging systems, and optical switching. One interesting application is a surface micro-machined noninvasive glucose-monitoring device based on optical coherent detection and polarimetric rotation sensing. This noninvasive device could potentially provide an alternative to the current painful method of monitoring blood glucose for millions of diabetes patients. This talk will also discuss MEMS optical switching that has attracted intensive research efforts in recent years. A closed-loop controlled 3-D MEMS optical cross-connect (OXC) will be presented as one example. At the end, this talk will briefly describe live-cell based bio-medical research with optical tweezers and high-resolution optical imaging, and discuss how MEMS and micro-optics can contribute to bio-medical research.

September 16, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Shamus McNamara of the University of Michigan and co-founder of PicoCal, Inc. will present A Light Touch: Sensing And Imaging With MEMS.  Abstract:  The application of MEMS and nano-technology to imaging and sensing applications frequently results in reductions in size and cost while simultaneously improving performance.  This talk will cover a diverse set of micromachined devices and the methods for fabricating them.  The premiere method of fabricating thick MEMS structures is LIGA, an x-ray lithography based process.  LIGA creates parts that are hundreds of micrometers thick with 0.1 micrometer tolerances, making it exceptionally useful for creating a variety of MEMS devices including motors, actuators, sensors, mirrors, gratings, etc.  The first on-chip vacuum pump combines sub-micron features and the principle of thermal transpiration for its operation.  The vacuum pump can be used for a variety of scientific instruments, including miniature chemical gas sensors.  The scan rate for scanning thermal microscopy has been greatly improved, enabling high throughput imaging over large areas for use in biological and nano-technology research.  The talk will conclude with a look at some of the exciting future directions of MEMS and nano-technology research.  Art Gmitro is the Colloquium host. 

September 10, 2004 -- Special Presentation -- 9:30 a.m. -- Meinel 701
Professor Stephen C. Rand of the Division of Applied Physics, Randall Laboratory, University of Michigan, Ann Arbor, will present Evolution to Revolution: From Nanoparticles to High Power Optical Ceramic Technology.  Abstract:  In recent years there has been a significant evolution in the development of high purity growth methods for nanoparticles in the 10 nm size range.  Concurrently, processing methods developed by Japanese researchers have led to the emergence of revolutionary laser-quality transparent ceramics prepared from rare-earth-doped nanopowders.  Output powers and efficiencies of kW class ceramic lasers have been reported to compare very well with those of crystal laser systems.  In this talk, we shall begin by describing powders synthesized by a high yield method at the University of Michigan that generate continuous-wave random laser action, exhibit quantum size effects, and sinter to translucency at exceptionally low temperatures.  Prospects for lasers and nonlinear optical devices based on long or large-aperture optical materials that combine several active functions (such as lasing and Q-switching) in a single piece without diffusion bonding will then be examined.  The relevance of final grain-size in optical ceramics to the persistence of quantum size effects and control of luminescent decay in these interesting new bulk materials will also be discussed.  Nasser Peyghambarian is the host.

September 9, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
Steve R.J. Brueck, Center for High Technology Materials Director and Professor of ECE, Physics and Astronomy at the University of New Mexico will present Phat Photons And Nifty Nanoscience.  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 48 nm for a l of 193 nm) as is shown in Figure 1. Immersion provides another factor of ~ 1.44 (H2O) down to a ½ pitch CD of 33 nm. 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. Both 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 will be discussed. An example of NHE for GaN on Si is shown in Figure 2. Photonic bandgap materials – with periodic arrays of nanoscale structures (with or without aperiodic defects) ‑ are another exciting example of the physics accessible with current interferometric lithography capabilities. Other applications that will be briefly highlighted include nanofluidics and infrared metamaterials. The overall message is that a nanoscale lithography capability enables many exciting nanotechnology research directions.  Nasser Peyghambarian is the Colloquium host. 

September 2, 2004 -- Optical Sciences Center Colloquium -- 3:45 p.m. -- Meinel 410
James C. Wyant, Optical Sciences Center Director and Professor will open the 2004-2005 Colloquium Series with It's Amazing What You Can Do With Interferometry.  Abstract:  While interferometry is an old topic and in my opinion there has been nothing new for at least 100 years, it is amazing how the addition of modern electronics, computers, and software has greatly increased the measurement capabilities of interferometry.  This talk will discuss some of the enhancements in the interferometric measurement of surface shape and surface roughness.  These measurement enhancements have made possible enormous improvements in the fabrication of precision optics, hard disk drives, machine tools, and semiconductor devices.  So if you love your iPod, your new high resolution digital camera, and your better mileage, lower pollution car, after this talk you will know how interferometry has helped improve your life.  Jose Sasian is the Colloquium host.