High-Sensitivity Temperature Sensor Based on Two Parallel Fabry–Pérot Interferometers and Vernier Effect

We propose a novel sensor with its temperature sensitivity improved by the Vernier effect. The sensor comprises two parallel Fabry–Pérot interferometers (FPI), namely, FPI1 and FPI2, which have a similar free spectral range (FSR) to obtain the Vernier effect. FPI1 and FPI2 are formed by a single-mode fiber inserted into a ceramic ferrule and an UV-curable glue film on the end surface of the ceramic ferrule. Since the UV-curable glue is a thermally sensitive material, FPI1 is very sensitive to temperature. The experimental results show that the temperature sensitivity of the proposed sensor is up to −14.633 nm/°C, which is 9.6 times that of the single FPI1 temperature sensor (1.5271 nm/°C). The sensor elaborated has a simple structure, good repeatability, high sensitivity, and low cost. It can be easily fabricated and has broad application prospects.