High-Sensitivity Temperature Sensor Based on Transmissive Solc-Like Filter and Cascaded Fiber Bragg Grating

A high-sensitivity temperature sensor is proposed, which is based on a cascade of transmissive Solc-like filter and fiber Bragg grating (FBG). The sensor combines rough measurement with precise measurement to expand the measurement range with high sensitivity. The Solc-like filter based on two spliced polarization maintaining fibers (PMFs) realizes high-sensitivity measurement by the Vernier effect. The mathematical model of transmission spectrum is established by the Jones matrix, and the relationship between the splicing angle and the interference fringes is proven. Also, the experimental results demonstrate that the measurement range is expanded by eight times after the filter is cascaded with the FBG. The highest sensitivity of the sensor is −57.35 nm/°C in the range of $-4.5\,\,^{\circ }\text{C}$ to 23.5 °C and the resolution reaches $3.49\times 10^{lpzrptMinus4}\,\,^{\circ }\text{C}$ . In addition, the result demonstrates that the amplification factor and sensitivity increase as the measurement range wider, so the sensor has great application potential in high-sensitivity temperature measurement.