Ultra-Wide Detection Range of Fiber Optic Temperature Sensor Based on Polydimethylsiloxane Film-Coated Tapered Single-Mode Fiber

Abstract This paper proposed a fiber optic temperature sensor with an ultra-wide detection range based on the polydimethylsiloxane (PDMS) film-coated tapered single-mode fiber (SMF). The SMF was tapered at first and then coated with a PDMS film to construct a Mach-Zehnder interferometer (MZI). The PDMS, which has a high thermo-optical coefficient and high light transmittance, was used to enhance the temperature measurement sensitivity in a wide temperature range. Combining it with a fiber Bragg grating (FBG), the device was capable of operating over a wide range of temperature, from −30 °C to 200 °C. The maximum temperature sensitivity was 3.437 nm/°C and the average sensitivity was 1.777 nm/°C. The techniques presented in this paper can be applied to other interferometric fiber optic sensors by combining the FBG to achieve beyond free spectrum range (FSR) measurement. The proposed temperature sensor has the ease of fabrication, high sensitivity, and a wide detection range, showing its application prospects in temperature sensing.