A Temperature-Insensitive Closed Chamber Gas Pressure Detection Method Based on Double-Layer Fiber Bragg Grating

Real-time monitoring of gas pressure inside a sealed gas chamber is a crucial aspect of the gas sensing field. To address the issue of cross-sensitivity between stress and temperature in fiber optic gas pressure sensors and achieve precise and linear measurement of gas pressure, this research proposes a detection method based on a double-layer fiber Bragg grating (FBG) string. This method enables accurate detection of changes in gas pressure within a closed chamber without temperature interference. To mitigate the issue of stress and temperature crosstalk, a pair of FBGs are vertically connected in series using a double-layer design approach. In addition, the sensor’s performance parameters can be determined through the use of control variates. Experimental results demonstrate that within the range of 100–300 kPa, the gas pressure sensitivity is 6.1 pm/kPa. The gas pressure detection error rate falls within the range of 0%–1.81%, and the sensitivity to temperature is 0.01 pm/°C, manifesting minimal impact from temperature variations. Furthermore, the sensor exhibits excellent repeatability and reproducibility, making it highly promising for a wide range of applications.