Polarimetric Er3+-doped fiber distributed-feedback laser sensor for differential pressure and force measurements

We propose and demonstrate a polarimetric Er3+-doped fiber distributed-feedback laser sensor in which a force applied transversely along the fiber laser induces a birefringence that gives rise to a change in the beat frequency between the two orthogonally polarized laser modes. We measure a sensitivity of similar to 9.6 GHz/(N/mm), a wide dynamic range with stable two-mode operation for frequency separations up to 50 GHz, and high sensor resolution owing to the narrow beat frequency bandwidth of <10 kHz. The temperature sensitivity is dominated by the temperature dependence of the inherent birefringence, which was measured to be -130 kHz/degrees C. The sensor permits independent pressure-force and temperature measurements. (C) 1996 Optical Society of America