Large-range and high-sensitivity fiber optic temperature sensor based on Fabry–Pérot interferometer combined with FBG

A compact fiber optic temperature sensor based on the Fabry–Pérot interferometer (FPI) combined with FBG is analyzed and demonstrated experimentally in this paper. The FPI is fabricated by splicing a single mode fiber (SMF) with a section of silicon tube filled with ultraviolet (UV) glue to form an air microcavity. Owing to the high thermo-expansion coefficient of UV glue, the sensor can achieve a high sensitivity. Besides, the cascaded FBG can be used to locate different temperature intervals, and therefore the detectable temperature range is largely extended. Experimental results indicate that the sensor has a temperature sensitivity of −4.665 nm/°C in a wide temperature range of −30 to 15 °C. In addition, our fiber temperature sensor also exhibited excellent consistency, good repeatability, and stability during the thermal cycle tests. Therefore, it has a good practical prospect.