A High-Sensitivity Fiber-Optic Fabry-Perot Gas Pressure Sensor With Epoxy Resin Adhesive

Abstract

A high-sensitivity fiber-optic gas pressure sensor based on a Fabry-Perot interferometer filled with epoxy resin adhesive is proposed. The factors of affecting the pressure sensitivity are theoretically analyzed and verified experimentally. In our experiment, the pressure sensitivity of the epoxy-filled sensor with the thinnest diaphragm thickness of $6.61~\mu \text{m}$ corresponding to the cavity length of $65.45~\mu \text{m}$ is -530.17 pm/kPa from 200 to 300 kPa. The sensitivity of the proposed pressure sensor with the shortest cavity length of $90.43~\mu \text{m}$ corresponding to the film thickness of $10.65~\mu \text{m}$ is -378.18 pm/kPa from 200 to 300 kPa. To further improve the sensitivity, the proposed pressure sensor is optimized, which consists of two cascaded Fabry-Perot interferometers separated by a long section of single-mode fiber to form Vernier effect. Such a pressure sensor based on the epoxy-filled Fabry-Perot interferometer and the Vernier effect obtains a high sensitivity of 2.526 nm/kPa in the local measurement range of 233 to 259 kPa and a low detection limit of 0.00892 kPa. With the advantages of high sensitivity, compact structure and simple fabrication, the proposed pressure sensor has potential applications in the biomedical field and ocean exploration.