SIMULTANEOUS STRAIN AND TEMPERATURE MEASUREMENT USING COMBINED FIBER AND FIBER BRAGG GRATING SENSORS

We propose here a new technique for simultaneous strain and temperature measurement using a Fiber Bragg Grating sensors. This technique employs an interferometric detection using two Fiber Bragg Gratings. A fiber Bragg grating is used as a reference while another fiber Bragg grating and a length of a bare fiber are used as the two sensing elements. As the temperature and strain change, the length of the sensing elements, (Fiber and Fiber Bragg Grating) change. These changes result in a phase and wavelength shifts. To measure these effects we use a Folded Mach Zhender interferometer, and a detection system made out of two photodiodes and data processing system. The sensitivity and dynamic range are analyzed and presented.