PDMS-Assisted Microfiber M-Z Interferometer With a Knot Resonator for Temperature Sensing

We experimentally demonstrate a compact temperature sensor using a microfiber-based Mach-Zehnder interferometer with a knot micro-ring resonator. The arm with a knot micro-ring resonator is embedded in polydimethylsiloxane (PDMS), which acts as the temperature transducer. The scattering matrix method is employed to establish the numerical model of the device. Owing to the high thermo-optic coefficient of PDMS, the response spectrum of the device will blue-shift when the ambient temperature increases. The device is characterized by changing temperature in two different environments (air and liquid), respectively. For temperature sensing operated in air, the device is tested utilizing a heating platform, which shows a sensitivity of -35.12 pm/degrees C when the temperature of the heating platform varies at a range of 15.5 degrees C. After that, a sensitivity boosting up to -41.58 pm/degrees C is measured when the device is immersed in a salt solution (25 parts per thousand in concentration) with the temperature changing from 22.2 degrees C to 32.9 degrees C.