Highly sensitive temperature sensor using femtosecond laser direct writing tapered fiber and coated with PDMS

This manuscript introduces a novel temperature sensor utilizing a Mach-Zehnder interferometer (MZI) created using direct femtosecond laser writing. The sensor is developed by modifying the core of a tapered single-mode fiber (SMF) with a femtosecond laser, which effectively excites the cladding modes to produce the MZI. Subsequently, the MZI is enclosed in polydimethylsiloxane (PDMS). According to experimental results, at a tapered fiber diameter of 30 mu m, the temperature sensitivity is 76.8 p.m./degrees C. The temperature sensitivity can be as high as 616.3 p.m./degrees C after the PDMS encapsulation, within a temperature range of 30-65 degrees C. Apart from enhancing the mechanical properties of the device, the PDMS packaging elevates its temperature sensitivity by eight times. This device is suitable for temperature measurement due to its uncomplicated structure, ease of manufacturing, durability, high sensitivity, and stable design.