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

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