Sensitivity enhancement of fiber-optic temperature sensor via lateral angled-offset splicing

In this letter, we report a fiber-optic temperature sensor based on the polarization-maintaining-fiber Sagnac-loop interferometer (PSLI) by the lateral angled-offset splicing. The group-time-delay of transmission of a panda-type polarization-maintaining fiber is investigated, and the optimal angle and lateral-offset of splicing are theoretically and experimentally gained. The results show that the temperature response of PLSI is significantly enhanced owing to high thermal expansion coefficient. Under the state of 45°-angle and 12-μm-offset, ~88% improvement of temperature sensitivity is gained and the maximum reaches 3.01 nm/°C with the detection limit of ~0.02 °C. Owing to the merits of ease of fabrication and low cost, the proposed sensor is very practical and promising for high-precision temperature-related engineering monitoring.