Sensitivity enhancement of a fiber grating temperature sensor combined with a bimetallic strip

ABSTRACT We attached a fiber Bragg grating (FBG) temperature sensor onto a bimetallic strip to increase the temperature measuring sensitivity. The temperature‐induced deflection of the strip strained the FBG sensor, increasing the amount of the Bragg wavelength shift in addition to the temperature‐induced one. The total Bragg wavelength shift ratio of the suggested sensor has been measured to be about four times larger than that of the intrinsic fiber grating sensor. This sensitivity enhancement enables to sustain the measurement accuracy even with low‐cost FBG interrogators, which have simple structure and modest wavelength resolution. With experiments in various conditions, the sensitivity characteristics according to the bimetal parameters were analyzed and the feasibility of the suggested sensor has been tested. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1926–1929, 2014