Wavelength-shifted chirped FBGs for temperature compensated strain measurement

Fiber Bragg grating (FBG) is the most researched and implemented sensor of all the available fiber optic sensors till date. Despite being highly sensitive and accurate, the applications of FBG sensors are limited. The main reasons for their limited applications are the high cost and bulkiness of the interrogation system, optical spectrum analyzer (OSA). In this paper, a wavelength shifted chirped FBG (CFBG) interrogation system is presented. It is an optical intensity based FBG interrogation system which can measure positive/negative strain and temperature changes simultaneously. This system is simple, cost effective, and compact with a strain resolution of around 1 με. A chirp bandwidth of 5 nm can easily provide a strain measurement range of about ±4000 με. Essentially, this sensor design abrogates the need for OSA and makes FBG more suitable for field applications.