High-temperature-resistant gas pressure sensor based on an all-silica Fabry-Perot interferometer

A high-temperature-resistant gas pressure sensor based on an all-silica Fabry-Perot interferometer (FPI) structure is proposed. A carbon dioxide (CO₂) laser is utilized to achieve integrated welding between a silica capillary tube and optical fibers. A cascaded femtosecond laser-inscribed fiber Bragg grating is used to compensate for the influence of temperature. The cavity length of the FPI is linearly correlated with gas pressure. Therefore, the pressure can be measured by analyzing the optical path difference of the FPI. Experimental results demonstrate that the sensor exhibits good linearity within a pressure range of 0-14 MPa, with a sensitivity of 58 nm/MPa and an error of 0.8% full scale (F.S.). It can measure 0-3.2 MPa gas pressure stably in an environment of 25-655°C. The sensor features a compact structure and shows broad application prospects in fields such as safety monitoring, energy power, and geological exploration.