Ultrasensitive fiber temperature sensor based on Fabry Perot interferometer and Vernier effect

Temperature is undoubtedly one of the most important parameters in human life, production, and technological activities, and plays a crucial role in both daily life and industrial production. Fiber temperature sensors, with their advantages of small size, fast response, high sensitivity, and so on, have been widely studied and used. Ultrasensitive fiber temperature sensor based on the Fabry Perot interferometer (FPI) and vernier effect has been composed. Single mode fiber (SMF), polydimethylsiloxane (PDMS), and capillary have been used to fabricate two FPIs. The sensor was cascaded by a sensing FPI (FPIs), a "SMF-PDMS-SMF" cavity with FSR of 6.27 nm, and a reference FPI (FPIr), a "SMF-capillary-SMF" cavity with FSR of 6.47 nm. Temperature measurements have been performed on both individual sensing FPIs and cascaded sensor, and it is found that they both have excellent linear response with linearity of more than 0.998. The sensitivity of the single sensing FPI is 1.037 nm/°C; The temperature sensitivity of the sensor based on the cursor effect is 32.39 nm/°C, with an amplification factor of 31.58, which is very close to the theoretical M-factor. This ultrasensitive temperature sensor can meet the demand for high-precision temperature measurement.