High-sensitive temperature sensor with parallel PDMS-filled FPIs based on dual Vernier effect

A novel high-sensitive temperature sensor with parallel polydimethylsiloxane (PDMS)-filled Fabry–Perot interferometers (FPIs) based on dual Vernier effect was proposed and demonstrated. The sensor is composed of two parallel FPIs with similar free spectrum range fabricated by splicing a section of silica tube to single-mode fiber. One is partially filled with PDMS to form an air cavity, and the other is fully filled with PDMS to form a PDMS cavity. Owing to the difference structures of two FPIs and the excellent characteristics of PDMS, the reflective spectra of two FPIs shift to opposite directions with the changes of ambient temperature. Two FPIs serve as reference FPI for each other in temperature measurement, resulting in the dual Vernier effect to enhance Vernier effect. The experimental results show that the proposed sensor exhibits a high temperature sensitivity of 7.61 nm/°C with good linearity. This work provides a new strategy for the fiber-optic sensing field.