Temperature sensor based on second-order PbS fiber Solc-Sagnac interferometer

Abstract In this paper, a temperature sensor based on a second-order PbS fiber Solc-Sagnac interferometer is presented. The PbS fiber and the two sections of single-mode fiber (SMF) are spliced together, it is named SMF-PbS-SMF structure. The light passes through the coupler and is divided into two beams of equal power, which are propagated in the Sagnac loop and travel through the two PbS fibers. The interference occurs after re-coupling of the two polarization controllers. The theory of temperature-sensitive birefringence effect in PbS fiber is analyzed and used for temperature sensing. The experimental results show that the transmission spectrum is red-shifted with increasing temperature, and the temperature sensitivity is 55.1 pm/°C in the range of 33.3 °C–78.8 °C. The proposed sensor has a simple structure and can be widely used in industrial production, biomedicine and other fields.