EM Labs & Centers at VT

Electromagnetics research at Virginia Tech ranges from the fundamental to the very applied. Research topics include antennas, wireless applications, fiber optics, sensors and materials, propagation, optical image processing, upper atmospheric processes, scattering, transients, as well as microwave modeling, measurements, design, and materials.

The Antenna Group performs research on new antenna geometries, analysis methods, and measurement techniques, working closely with industry and government to meet their needs. Several new antennas have been developed and are being used on a variety of applications. The recent advances in antenna research include:

The laboratory continues to expand its technology base and facilities. Efforts currently include new measurement systems and methods, evaluation of large electromagnetic codes, and a new emphasis on embedded antennas for use in handsets and mobile radio applications. In 2000, the Group began full use of its new $500,000 tapered anechoic chamber. The chamber includes both far-field and near-field measurement equipment. VTAG continues to use its roof top antenna range also.

EMIL continues to work toward obtaining a better understanding of how electromagnetic waves interact with the natural environment. On the applications side, EMIL is assisting NASA Goddard Space Flight Center in trying to determine the source of anomalous data coming from the TOPEX/POSIEDON radar altimeter. This same sensor first detected the onset of El Niño. Preliminary indications are that the sources of the anomalous data are the relatively smooth patches on the ocean’s surface that can frequently be seen from aircraft. The problem that EMIL is primarily involved in is modeling the effect of these on the radar, and designing ways to circumvent their contamination of the radar data. EMIL is also conducting an investigation for the U.S. Air Force to be able to predict when a radar can penetrate a canopy of foliage, propagate down to a target on the surface, and scatter back up to the radar with a detectable signal level. EMIL has developed one model that is particularly amenable to “calibration” by comparing the model with actual radar data. Such “calibration” ensures that the parameters in the model are derived from (limited) actual data with the aim of using the model to predict penetration over other similar regions. In a program sponsored by the Office of Naval Research, EMIL has developed a model for low-grazing electromagnetic wave scattering by the ocean surface that includes the refraction in the atmosphere above the surface. The inclusion of both refractivity and surface roughness is done in an exact manner and is particularly important in ship self-defense.

Propagation in an urban environment with particular emphasis on wave diffraction in the off-specular direction by objects having sharp edges is a project being sponsored by the U.S. Army Research Office. EMIL researchers have also developed the only known model for the effects of roughness on diffraction of an electromagnetic wave by a rough knife-edge boundary. Finally, EMIL is conducting basic research on new models for wave scattering by two-dimensionally rough surfaces that are both robust in their range of applicability and fast in their implementation. This research is sponsored by the University of Delaware, under a U.S. Air Force MURI on Computational Electromagnetics.

FEORC was founded at Virginia Tech by Virginia’s Center for Innovative Technology, primarily to provide university research to support development of the state’s fiber optics industry. Over the past 15 years, the lightwave industry has spread across the entire state, including an area with a high concentration of businesses in the southwestern part of Virginia known as “Silica Valley.” Since its inception, the Center has developed many intellectual properties that have been commercialized, including fiber optic sensors, couplers, and thin films.

FEORC developments during the past year include the incubation of a new research center on campus: the Optical Sciences and Engineering Research Center (OSER). OSER will focus primarily on the use of optics to provide new biological research tools for visualization, measurement, analysis, and manipulation for medical, biomedical, and veterinary applications. Areas of research include advanced laser surgery optics, biocompatible material for implants, and diagnostic patches and other diagnostic and drug delivery tools.

For several years, FEORC has collaborated with the Center for Transportation Research on the communications network for Virginia’s “Smart Road.” This multimillion-dollar test-bed highway is finally a reality, and well equipped for many ITS (intelligent transportation systems) applications. The optical fiber backbone of the network was installed in February, with the entire road becoming operational in March this year.

FEORC is currently involved in several new multidisciplinary programs including a university-sponsored ASPIRES program with the College of Veterinary Medicine for the optical detection of biological functions, and an industry- and government-sponsored program to develop new nano-structured electro-optic materials.

The Center’s mission within the university community is to teach graduate and undergraduate students about optical materials and devices, instrumentation and communications systems through research projects and formal classroom and laboratory teaching. FEORC has the largest fiber optics research and instructional program in the United States. Currently the Center has 20 full-time research staff members and more than 30 graduate students. Each year approximately 300 students take fiber optics related courses, such as fiber optics communications, networks and systems, polymer optoelectronic devices, fiber optic applications, and electrical theory, taught by four primary faculty members.

The Center’s efforts to provide support to industry in the state have been successful and, over the years, have included cooperative efforts with more than 250 Virginia companies and providing the impetus for the establishment of 17 spin-off firms in Virginia and one in Minnesota.

Gould Fiber Optics

Lockheed-Martin

Northrop Grumman

Boeing

Hughes

General Motors

Vitesse Semiconductor

SDL, Inc.

PMC-Sierra

Applied Microcircuits

Broadcom

General Dynamics

Raytheon

Intel

Texas Instruments, Inc.

The OIP Lab creates an environment for progressive, practical scholarship in all aspects of hybrid (optical/electronic/digital) information processing technology. Its comprehensive academic research and education program complements the growing need for photonic instrumentation and the economic development of the electro-optics industry. The OIP Laboratory supports research in the areas of acousto-optics, optical scanning holography, 3-D microscopy, real-time optical 3-D coding and decoding, and optical pattern recognition. Equipment includes two large vibration isolation optical tables with associated optical, mechanical, and electronic instrumentation. Specialized equipment includes an electron-beam-addressed spatial light modulator and an optically addressed spatial light modulator (long-term partnership loan from Hamamatsu Photonics K.K., Japan), and x-y optical scanning systems. More than 20 Sun-Sparc workstations can be accessed from the OIP Lab directly.

The program of the OIP Laboratory actively encourages the two-way transfer of technology between industry and the university, and mutual collaboration with other research institutes. Typical sponsors include Army Research Office, Hamamatsu Corporation, National Science Foundation, NASA, National Institutes of Health, and the U.S. Navy.

Established in 2000, the Optical Sciences & Engineering Research Center (OSER) investigates advanced laser surgery optics, biocompatible material for implants, and diagnostic patches and other diagnostic and drug delivery tools. The Center employs optics to provide new biological research tools for visualization, measurement, analysis and manipulation. The Optical Sciences and Engineering Research center (OSER) is part of a unique collaboration among Virginia Tech, the Carilion Health System and the University of Virginia. The umbrella organization for this partnership is the Carilion Biomedical Institute in Roanoke, Virginia. The institute is primarily responsible for prototype development, commercialization and the spin-off of technology created by its supporting research centers at the two universities: OSER at VT and the Medical Automation Research Center (MARC) at UVA.

Research center activities range from basic biomedical research to experimental device development and laboratory demonstrations. Results of center R&D activities are transferred to the institute for prototype and product development leading to new bio-technology start-up companies and the creation of new jobs in Virginia.

OSER at Virginia Tech focuses on advanced laser surgery optics, biocompatible materials for implants and diagnostic and drug delivery tools. MARC at the University of Virginia develops technology to contribute to laboratory efficiency such as robotic systems to transport and process blood specimens and other body fluids, and tools to speed the discovery of new drugs and to improve the understanding and treatment of genetic diseases.

The Photonics Laboratory was established in 1997 to focus on graduate education and research in photonics technologies. Photonics is the technology of generating, harnessing, and manipulating light to perform useful functions. The four laboratories within the Photonics Laboratory support research in the areas of a wide range of photonic devices and systems for sensing, imaging, and communications.

Although newly established, the Photonics Laboratory is earning a national reputation as a leader in photonic sensors for harsh environments for applications where conventional sensors and measurement devices are difficult to apply. Typical harsh environments are characterized by high temperature, high pressure, high voltage, strong electromagnetic interference, and/or chemically corrosive atmospheres. The Center’s research covers all the major aspects concerning optical sensors, including materials, new sensing mechanisms, fiber modifications, advanced packaging, signal demodulation, and instrumentation systems. The research has recently yielded a number of successful new sensors. Two examples are self-calibrated interferometric/intensity-based (SCIIB) fiber sensors capable of operation at temperatures up to 800^°C, and single-crystal sapphire fiber-based sensors for temperatures up to 2000^°C. The SCIIB technology for the first time successfully combines fiber interferometry and intensity-based devices into a single sensor system so it possesses all the major advantages of the two types while eliminating or minimizing their disadvantages. Experimental evaluations of various SCIIB pressure, temperature, strain and acoustic sensors have clearly shown simultaneous advantages of small size, high resolution, high accuracy, high frequency response, self-calibration, and absolute measurement. The unique design of the sensor renders it extremely insensitive to undesired perturbations, such as temperature, fiber losses, and source power fluctuations.

Silica glass fiber-based sensors are restricted to temperatures below 900^°C primarily because of the thermal diffusion of germanium dopants in the fiber core. With recent breakthroughs in bonding of high temperature materials and methods for splicing of glass fiber to sapphire fiber, researchers in the Photonics Laboratory were able to fabricate reliable sapphire fiber-based sensors, which can be reliably used at temperatures above 1000^ºC. Sapphire sensors are highly desirable in a wide range of industrial applications with harsh environments, since sapphire is very inert with respect to most aggressive chemicals, even at high temperatures. In addition to the single-point measurement capabilities, researchers are also developing techniques for multiplexing of thousands of sensor elements along a single fiber cable, which would permit measurement along a span of tens of miles at a low cost per measurement point. Moreover, to fully exploit the high frequency response capability offered by the miniaturized fiber sensor probes, the Photonics Laboratory is developing state-of-the-art DSP high-speed sensor signal processing.

In 3-D imaging, research has been focused on system miniaturization and cost reduction through technological innovations. The Laboratory has successfully developed several key optical or optoelectronic devices and systems. One example is the development of a miniaturized diode laser/polarization maintaining fiber-based illumination system, which replaced the gas lasers previously used in the holographic 3-D imaging products of the industrial sponsor. The replacement yielded a reduction in size, an increase in optical power, and a reduction in cost by several fold. Subsequent to the development of the laser/fiber source system, Virginia Tech then developed a miniaturized light illumination module (LIM), which generates specialized, encoded optical patterns based on the combined use of fiber optics, holograms, and spatial light modulators, for 3-D object mapping. The developed LIM has a size of 5x3.5x3 inches; the world’s smallest of its kind. Building upon this experience, the Center is developing all-fiber LIMs to further reduce overall instrumentation size and cost. Recently, the Center has moved further to combine commercially available thermal imaging devices with the developed 3-D mapping technology to acquire the capability of 3-D skin surface/temperature mapping desirable in many medical applications.

The Photonics Laboratory has done extensive work in special optical fiber waveguides for both sensing and communications. One example is a recent optimal design of a large effective area single mode optical fiber by Safaai-Jazi for long-haul telecommunications. The new design permits significant reduction in nonlinear optical effects in the fiber while maintaining a minimal level of chromatic dispersion and sensitivity to bending-induced losses. Another example is the recent successful development of special fiber waveguides, which allow effective optical coupling from a laterally incident laser beam into the fiber. Based on the specially modified fiber, a prototype off-axis optical slip-ring with a diameter of 1.5 meters was fabricated and a data rate as high as 300Mb/s of off-axis data transmission has been obtained. Such slip-rings are desirable in many military, medical and industrial systems, where broadband, EMI-free analog or digital signal transmission is needed. In addition to changes to fiber materials and refractive index profiles, the Photonics Laboratory has also done extensive work to evaluate a variety of specially coated optical fibers to determine their survivability and performance in harsh environments, such as pressurized water with elevated temperatures, and ultra-high temperatures in extremely corrosive atmospheres. Moreover, with a newly acquired vertical fiber preform lathe plus a fiber draw tower available in the Fiber & Electro-Optics Research Center, the Photonics Laboratory will soon gain a complete capability of fiber design, preform fabrication, and fiber drawing.

The Photonics Laboratory has an annual research budget of more than $2 million. It is supported by various federal and state funding agencies and companies. Some of the major current research sponsors include NSF, DOE’s National Petroleum Technology Office, DOE’s Federal Energy Technology Center, NASA Langley Research Center, Electric Power Research Institute, and Virginia Center for Innovative Technology.

Main research interest is in the area of wideband measurements and characterization problems using time domain and frequency domain techniques. This includes the development of the measurement techniques; the characterization and modeling of devices, networks, or materials; the development of the necessary signal processing and data reduction methods; and the design and construction of related measurement instrumentation and setups.

The Laboratory contains facilities for wideband measurements from DC into the microwave and millimeter wave (70 GHz) frequency regions. This facility enables wideband measurements in both the time domain and the frequency domain.