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 two polarization modes of a birefringent dual-longitudinal-mode moire distributed-feedback fiber laser are employed to measure strain and temperature simultaneously. Operating entirely in the rf domain, this approach potentially allows one to employ low-cost and precise rf measuring techniques. A strain-temperature cross sensitivity of the strain- and the thermo-optic coefficients, which can be neglected in wavelength-based grating sensors, has been observed. The achieved sensor accuracy was +/- 15 mu epsilon and +/-0.2 degreesC. (C) 2001 Optical Society of America.