Non-diaphragm fiber gas pressure sensor based on femtosecond laser machining

A non-diaphragm fiber gas pressure sensor fabricated using a femtosecond laser is proposed and experimentally demonstrated. This sensor is a type of low-precision extrinsic Fabry-Perot interferometer (EFPI) formed by sandwiching a hollow fiber (HF) between a single mode fiber and a no-core fiber. A femtosecond laser is used to drill a micro-channel on the side wall of the HF to allow the gas to enter and exit the HF. When the external gas pressure changes, the refractive index of the gas in the EFPI cavity changes. The gas pressure can be detected by determining the optical cavity length of the EFPI. The experimental results show that the pressure sensitivity in the cavity is 1.02 /zm/MPa in the pressure range of 0-5 MPa, and the pressure resolution of the sensor is 2.4 kPa. This pressure sensor has the advantages such as wide measuring range, high sensitivity, high resolution, and high linearity.