Distributed-feedback fiber laser sensor for simultaneous strain and temperature measurements operating in the radio-frequency domain

Radio-frequency (rf) beat frequencies between two longitudinal modes and tw o polarization modes of a birefringent dual-longitudinal-mode moire distrib uted-feedback fiber laser are employed to measure strain and temperature si multaneously. Operating entirely in the rf domain, this approach potentiall y allows one to employ low-cost and precise rf measuring techniques. A stra in-temperature cross sensitivity of the strain- and the thermo-optic coeffi cients, which can be neglected in wavelength-based grating sensors, has bee n observed. The achieved sensor accuracy was +/- 15 mu epsilon and +/-0.2 d egreesC. (C) 2001 Optical Society of America.