Abstract

Properly annealed fiber gratings can be used as sensor transducer elements at temperatures of 400° C over long periods of time without measurable changes. At 650° C, however, a problem was observed with creep or hysteresis of the grating response. At even higher temperatures diffusion of the core material will become a problem for long term operation. A couple new decoding schemes for fiber grating sensors use matched gratings and acousto-optic tunable filter in the decoding unit These systems can measure many grating transducer elements simultaneously with high sensitivity. Short cavity fiber lasers that utilized fiber gratings can also act as sensor transducer elements giving one ultra high sensitivities that are limited by the fundamental noise in the fiber. One fiber laser sensor uses hetrodyning to generate a signal that can be measured on an RF spectrum analyzer. New techniques for simultaneous measurement of temperature and strain will also be discussed.

© 1995 Optical Society of America