High sensitivity gas pressure sensor based on two parallel-connected Fabry–Perot interferometers and Vernier effect

In this study, a highly sensitive gas pressure sensor based on two Fabry–Perot interferometers (FPIs) in parallel with the Vernier effect is designed and demonstrated. In the sensor, FPI1 and FPI2 were used as the detection and reference units, respectively. FPI1 and FPI2 have similar structures, both comprising a single-mode fiber and capillary splicing. However, the microaperture is processed on the capillary of the FPI1 with a femtosecond laser, enabling the external gas to enter the FPI1 cavity through the microaperture channel to realize the gas pressure measurement. The Vernier effect is achieved by superimposing the reflective spectra of FPI1 and FPI2, which have a small cavity length. The gas pressure response, repeatability, and stability of the sensor structures were investigated. The sensitivity of the sensor was improved owing to the Vernier effect. Experimental results indicate that the sensor sensitivity is up to 47.76 nm MPa−1, which is 11.9 times that of a single FPI1 sensor without the Vernier effect. The measured temperature cross-sensitivity of the sensor is approximately 5.1 kPa/ °C. In addition, the sensor has the advantages of simple manufacturing, robust structure, and stable operation. Finally, the manufacturing method of FPI and the parallel connection mode of FPIs could also be used in other sensing fields, providing an alternative design scheme for high-sensitivity sensors.