Fiber-tip air cavity sealed by cutting-free inwardly concave silica diaphragm cascaded to fiber Bragg​ grating for gas pressure sensing

Fiber-tip air cavity sealed by cutting-free inwardly concave silica diaphragm cascaded to fiber Bragg grating for gas pressure sensing is proposed. According to the measured experimental data, the proposed fiber-tip air cavity respectively has its pressure sensitivity of 9.79 nm/MPa, temperature sensitivity of 2.61 pm/°C which induces a pressure detection error of 3.55 kPa/°C. The experiment results show that the proposed fiber-tip air cavity possesses the advantages of appropriate pressure measuring sensitivity, low temperature sensitivity and temperature induced pressure detection errors, and it is suitable for practical gas pressure sensing. •The moderate pressure sensing sensitivity that to avoid the challenge of ultra-wide interrogation bandwidth.•The examined FPI with the advantages of enlarged sensing surface than flat reflectors, cutting-free diaphragm to avoid the needless non-sensing area which attached onto the surface of cylindrical cavity that may lead to detection errors.•The inwardly concave diaphragm fused into hollow core silica tube (HST) can effectively shorten the air cavity length to lower the standards on minimum cutting length of high-precise cutting platform for HST segment cutting.