Fiber Bragg grating vacuum sensors

Abstract

This letter demonstrates functional enhancements of fiber Bragg grating sensors powered by in-fiber light. High-power laser light transmitted in double-clad optical fiber was extracted from the fiber core to heat an on-fiber metal coating. When the power-laser is turned off, the fiber Bragg grating is used as a passive component for temperature sensing. When the laser is turned on, the thermal response of the optically heated grating was used to monitor ambient air pressure. The sensitivity and dynamic range of optically powered fiber sensors can be actively adjusted by in-fiber light to measure vacuum pressures over four orders of magnitude.