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Press Releases Newsletters
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PSI's Nonlinear Optics and Applications Group at San Ramon, CAFor over three decades, Physical Sciences Inc. has developed new applications for lasers and other electro-optical
devices. These include research and industrial sensors based on tunable laser spectroscopy, as well as medical
diagnostics and environmental monitors.
In recent years, we have been developing the laser sources themselves, for both civilian and military applications.
Our Q-Peak subsidiary manufactures a family of pulsed and CW solid state lasers that are used in LIDAR and LADAR
systems, and our Laser Technologies Group at PSI has recently introduced an all solid state dye laser.
In this issue, we describe an exciting new activity at our San Ramon, CA laboratory that exploits nonlinear optical
conversion technologies for the generation of laser light from the visible to far-infrared wavelengths. These
efforts are closely integrated with system development activities and experimental programs at our Andover, MA
facility. For more information, contact Dr. Mark Allen allen@psicorp.com Nonlinear Optics and ApplicationsPSI recently formed the Nonlinear Optics and Applications Group, led by Douglas Bamford. Based in PSI's San Ramon office, this group develops new sources of laser radiation, typically based on the nonlinear frequency conversion of existing lasers, and applies these new laser sources to the solution of our customers' problems. Engineered nonlinear optical devices, based on micron-scale patterning of ferroelectric materials, are used to convert radiation from diode lasers and diode-pumped solid state lasers (which typically operate in the near-infrared region of the spectrum) to longer (mid-infrared) or shorter (visible) wavelengths.
As an example, Coherent Technologies Incorporated (CTI) was charged with developing a solid-state laser source that could produce a high-average-power yellow laser for the excitation of sodium atoms in the atmosphere. This excitation creates an “artificial star”, which can be used by astronomers to correct for atmospheric distortion and thus obtain clearer images of faint objects in the cosmos. To generate the yellow light, it was necessary to excite a nonlinear optical crystal with two lasers operating in the near-infrared region of the spectrum. After the commercially available nonlinear optical materials proved unable to generate the power required for this application, CTI approached PSI.
A crystal of a new nonlinear optical material being developed by David Cook, Scott Sharpe, and Aaron Van Pelt, called “periodically poled stoichiometric lithium tantalate”, allowed CTI to meet the application requirements. A laser system based on this crystal has now been installed at an observatory. Mid-infrared laser sources, pumped by semiconductor diode lasers, have been packaged into instruments used for atmospheric monitoring (water vapor, methane), isotope ratio measurement (carbon dioxide), and industrial process control (methane, ethylene). Recently the group has demonstrated a diode-pumped mid-infrared source with an exceptionally wide tuning range that can be used to detect almost any molecule containing a carbon-hydrogen bond.
Semiconductor materials are being used by David Cook and co-workers to convert radiation from solid-state lasers (also operating in the near-infrared) into the far-infrared region of the spectrum, also called the terahertz region. A terahertz spectrometer based on a frequency-converted ultrafast laser is used to perform basic absorption spectroscopy measurements on target materials. This instrument has identified absorption lines that can be used for selective detection of crystalline species, such as explosives, even when those species are surrounded by other materials, such as mailing envelopes. Using this new spectroscopic information, portable instruments aimed at detecting the target species in the field are being developed.
Many of these technologies are expected to follow the same pathway to commercialization that has been established at PSI for gas sensors based on near-infrared diode lasers. First-generation prototypes, developed for customers in the research community, are used as the basis for developing ruggedized instruments suitable for industrial applications. Because absorption lines in the mid-infrared “fingerprint” region of the spectrum are typically much stronger than absorption lines in the near infrared, more sensitive instruments can be developed for the same target gases. PSI Welcomes Aaron Van Pelt
Aaron Van Pelt, Senior Research Scientist, recently joined the San Ramon office. Aaron is working in the Nonlinear Optics and Applications Group developing new laser sources based on engineered nonlinear optical materials and on applying these sources to industrial process control. Upcoming projects include using ultrafast lasers to generate terahertz radiation for terahertz spectroscopy applications.
Aaron was previously an applications engineer and later a product manager at New Focus, Inc. where he led the design of optoelectronic, optomechanical and laser-based products for OEM customers and for the photonics research market. Aaron's work in graduate school at Washington State University involved ultrafast, time-domain spectroscopy used to investigate carrier dynamics in solids. Upcoming Presentations- D. Cook, M. Allen, B. Decker, R. Wainner, J. Hensley, H. Kindle, “Detection of High Explosives with THz
Radiation”, Joint 30th International Conference on Infrared and Millimeter Waves and 13th International Conference
on THz Electronics, 19-23 Sepember 2005, Williamsburg, VA. Contract NewsPSI recently received several government contracts including: “Multiplexed Drug Discovery Assay for Neurodegeneration” from National Institutes of Health; “On-Line Aircraft Fuel Tank Oxygen Sensor” from the Air Force Research Laboratory at Wright Patterson Air Force Base; and “Infrasonic Frequency Seismic System for Pipeline Integrity Management” from the Department of Transportation. Editor Donna Lamb lamb@psicorp.com Contributors Mark Allen, Doug Bamford, Aaron Van Pelt, and R. Weiss A publication of
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