NASA 1996 SBIR Phase I

PROJECT TITLE : Solid-State Spectroradiometer

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

The design and development of a solid-state spectroradiometer for operation in the near infrared wavelength range of 1.8 to 2.4 *m is proposed. This device utilizes a laterally graded GaxIn1-xAsySb1-y waveguiding/detecting layer formed by liquid phase epitaxial deposition onto a continuously moving substrate to monolithically integrate a linear array of photodetectors with different spectral absorption properties. Since each photodetector is designed to detect light of a discrete wavelength range, the spectroradiometer can determine the precise spectral content of an unknown signal. In addition, each photodetector provides an accurate measure of the intensity of the particular spectral component. Measurement of thermal radiation in the 1.8 to 2.4 *m wavelength range will determine information about the chemical and physical state of the atmosphere as well as the skin temperature and reflectivity of the earth surface. This program will explore the limits of the moving substrate epitaxial growth technique in forming laterally graded layers. The Phase I program will demonstrate the feasibility of the laterally graded epitaxy process and the fabrication and characterization of photodetector arrays. In the Phase II program, the device structure will be further developed to extend its specroradiometric range to wider bandwidth signals with improved resolution.

Completion of this program will lead directly to the fabrication of low-cost solid-state spectroradiometers. These devices are compact and highly portable; they require no moving parts and are therefore very stable and precise. The measurement of thermal radiation in the 1.8 to 2.4 *m wavelength range will facilitate a wide variety of spectroscopic applications including absorbance/transmittance, reflectance, and emission analysis. These measurements will provide valuable information about the chemical and physical state of the atmosphere as well as the skin temperature and reflectivity of the earth surface. An additional application for this technology includes wavelength division multiplexing in optical communication systems employing ultra-low loss fluoride glass fibers.

Zane A. Shellenbarger
AstroPower, Inc.,
Solar Park, Newark, DE 19716-2000

AstroPower, Inc.,
Solar Park, Newark, DE 19716-2000