Optical Fiber Temperature Sensor Based on PDMS-Filled Air-Cavity Fabry–Perot Structure

Seawater temperature is one of the important basic parameters in oceanography, which involves many fields such as aquaculture, marine meteorology, navigation, etc. In this paper, a high-sensitivity temperature sensor based on Polydimethylsiloxane (PDMS) filled air-cavity fiber Fabry-Perot (FP) structure is proposed. It is composed of capillary quartz tube, single-mode fiber, and PDMS. According to the temperature experiments, the proposed sensor can achieve a high temperature sensitivity (no less than 7.34611 nm/°C or even more) with good repeatability and good response time in the measurement range of 0 °C to 40 °C. The standard deviation of the probe 1 is 0.03903 nm (0.00483 °C) at 30 °C, while that of the actual environment temperature is 0.00452 °C. Only a small deviation existed between proposed sensor’s result and actual environment temperature. Additionally, the proposed sensor still exhibits high stability in environments with temperatures of 10°C and 20 °C. Moreover, it could easily achieve temperature measurement with high sensitivity and large range simultaneously by using cavity length demodulation method.