Research on highly sensitive Fabry-Perot cavity sensing technology in frozen soil

A high-sensitivity low-temperature sensor based on Fabry-Perot interferometer (FPI) is fabricated and experimentally demonstrated in this letter. The FPI air cavity is fabricated by splicing a single-mode optical fiber (SMF) with a glass capillary tube partially filled with ultraviolet (UV) glue. Due to the high coefficient of thermal expansion of UV-glue, the sensor can obtain high sensitivity. Experimental results show that the sensor has a temperature sensitivity of -3.753 4 nm/degrees C in the temperature range of -4-4 degrees C, and the linearity is 0.999. The engineering performance of the sensor is tested by simulating the frozen soil environment. The proposed sensor has high sensitivity and good temperature response. The sensor structure is compact and simple, low cost and has potential application in the cryogenic detection environment.