A High-Sensitive Fiber-Optic Fabry-Perot Sensor With Parallel Polymer-Air Cavities Based on Vernier Effect for Simultaneous Measurement of Pressure and Temperature

A novel high-sensitive fiber-optic Fabry-Perot sensor with parallel polymer-air cavities based on Vernier effect was proposed and demonstrated for simultaneous measurement of pressure and temperature. The sensor is composed of two parallel Fabry-Perot cavities both are fabricated by splicing a section of silica tube to the single-mode fiber. One cavity is filled with polydimethylsiloxane, and the other cavity is filled with a thin layer of ultraviolet glue at the end-face of silica tube, ensuring that the free spectrum ranges of two Fabry-Perot cavities are similar and generate the Vernier effect. The Fabry-Perot interferometer filled with polydimethylsiloxane was found to be sensitive to pressure as well as temperature, whereas the Fabry-Perot interferometer filled with a thin layer of ultraviolet glue was sensitive to pressure only. Owing to the different features of two Fabry-Perot interferometers, the sensor achieved simultaneous measurement of pressure and temperature. Combined with Vernier effect, the sensor provided a pressure sensitivity of −36.93 nm/MPa and a temperature sensitivity of 10.29 nm/°C, respectively. The sensor has exhibited potential applications in fields of medical diagnostics, environmental monitoring, and biological sensing.