Theoretical Investigation of Mid Infrared Temperature Sensor Based on Sagnac Interferometer Using Chloroform Filled Photonic Crystal Fiber

In this paper, a novel Sagnac Interferometer (SI) based chalcogenide Photonic Crystal Fiber (PCF) temperature sensor is theoretically and numerically analyzed operating in the mid infrared (MIR) region. The PCF cladding air holes are proposed to be filled with a highly temperature sensitive liquid chloroform to enhance the temperature sensitivity. The temperature sensing characteristics of three different infiltration technique is investigated theoretically and compared by Finite Element Method (FEM). Simulation results show that full infiltration performs better than partial infiltration. In the numerical analysis two sensing dips with high linearity is achieved for full infiltration which shows sensitivity of −5.77 nm/°C and 8.49 nm/°C when the temperature increases from 25 to 85 °C for the specific fiber length of 1.532 mm. The R2 values are 0.957446809 and 0.97680771 for the respective two sensing dips. The proposed highly sensitive sensor has broad detection window which can be applied in fingerprint unlocking, MIR radiation detection in human body, biomedicine applications, and environmental temperature monitoring.