Ultra-sensitive air pressure sensor based on gelatin diaphragm-based Fabry-Peroy interferometers and Vernier effect

Abstract

We proposed and experimentally demonstrated a gelatin diaphragm-based Fabry-Perot interferometer (FPI) structure ultra-sensitive fiber optic air pressure sensor. The Fabry-Perot (F–P) cavity of the sensing probe FPI1 is made of gelatin diaphragm, with a thickness of approximately 0.8 μm and the probe length of approximately 136 μm. The air pressure sensitivity of the probe obtained in the experiment is as high as 334 nm/MPa. In order to further improve the sensitivity of the probe, we fabricated an FPI2 with an air F–P cavity that is approximately the length of the FPI1 cavity, and then paralleled FPI2 with FPI1 to generate a Vernier effect. The average sensitivity of the Vernier probe obtained in the experiment reached −2650 nm/MPa, which magnified the sensitivity of a single FPI1 by about 7.9 times. The temperature cross-sensitivity is only 3.6 kPa/°C. This proposed air pressure sensor has the advantages of ultra-high sensitivity, simple manufacturing, low cost, good repeatability and stability, and has broad application prospects in high sensitivity pressure and acoustic detection.