Sensitivity-Enhanced Temperature Sensor Based on PDMS-Coated Mach–Zehnder Interferometer

A sensitivity-enhanced temperature sensor based on a Mach-Zehnder interferometer (MZI) coated by polydimethylsiloxane (PDMS) film is proposed and investigated. The MZI with a compact size of 2.28 mm is fabricated by embedding a tapered single-mode fiber (SMF) between two multimode fibers (MMFs). Since PDMS has a higher thermo-optical coefficient than silica, the proposed sensor has better temperature sensing performance than the case without PDMS coating, which is demonstrated by simulation and experiment. The experimental results show that the sensitivity of the proposed sensor is as high as -1.06 nm/°C in the range from -5 °C to 45 °C.