A High-Sensitivity and High-Temperature-Resistant Gas Pressure Sensor Based on Open Hollow-Core Fibers Fabry–Pérot Interferometer Probe

The pressure sensors capable of high sensitivity and wide measuring range at high temperature are urgently needed in many industrial fields. We propose a novel fiber-optic Fabry-Pérot interferometer (FPI) probe gas pressure sensor based on hollow-core fibers (HCFs) offset fusion splicing. Two HCFs with different inner diameters construct an open FP cavity that allow gas to enter. Pressure is detected by demodulating the change in optical path difference of FPI caused by the variation in refractive index of air. From the experiment results, the sensor has a high sensitivity of 4.04 μm/MPa over large pressure range of 0-14 MPa, which presents the ultra-low pressure-temperature cross-sensitivity of 0.18 kPa/°C with the capability of surviving high temperature up to 1100 °C. A fiber Bragg grating is integrated into the FPI structure for temperature sensing and error correction. The proposed sensor has the properties of high-temperature resistance and small size, which can be applied in high-temperature and harsh environment.