SIMULTANEOUS MEASUREMENT OF STRAIN AND TEMPERATURE WITH POLARIZATION MAINTAINING FIBER BRAGG GRATING LOOP MIRROR

A novel simultaneous method of strain and temperature measurement based on a polarization maintaining fiber Bragg grating loop mirror is proposed and demonstrated. The sensing head was composed of a fiber loop mirror and a section of fiber Bragg grating made of a polarization maintaining fiber. The Bragg wavelengths of the fiber grating in the polarization maintaining fiber were along slow and fast axis showing different sensitivities to strain and temperature with the interferometric peak wavelength of the fiber loop mirror. By monitoring the shifts of the Bragg wavelength and interferometric peak of the fiber loop mirror, with its temperature sensitivity of 0.1167nm/degrees C and strain sensitivity of 0.0093nm/mu epsilon, a temperature measurement resolution about 0.009 degrees C and a strain measurement resolution of 1.08 mu epsilon was achieved theoretically and experimentally.