Abstract

The use of optical fibers for chemical monitoring predates communications uses. In recent years, advances in fiber optic and semiconductor technology, as well as in analytical chemistry and biochemistry, have made fiber optic chemical sensors very attractive for a wide variety of environmental applications. Remote spectroscopic measurements via optical fibers (passive fiber optic chemical sensing), including fluorescence and Raman spectroscopy, and often multiplexing many fibers to provide simultaneous multipoint chemical information, have become well accepted in the process control and environmental monitoring industries. Active techniques, in which chemically sensitive devices, or “optrodes”, are attached to fibers, are being intensively studied, and a few sensor systems based on these are beginning to appear as commercial products. Intrinsic sensors, in which optical fibers are the actual chemical transduction devices, have begun to attract wide attention, because of their potential for continuous long-path monitoring. Chemical sensing requirements challenge fiber optic researchers: new optical fiber designs (D-fibers, hollow waveguides, multi-core, off-center core, tapered geometries, and others) are being investigated to enhance fiber chemical sensitivity. New fiber materials (fluorozirconate, chalcogenide, sapphire, silver halide, and others) are being developed to extend transmission into the infrared “chemical fingerprint” region of the electromagnetic spectrum.

© 1993 Optical Society of America