Large-scale and High-density Hydrogen Sensor Based on OFDR and Weak Fiber Bragg Grating Array

A large-scale and high-density hydrogen sensor is proposed by integrating a Pt/WO₃ coated identical weak fiber Bragg grating (WFBG) array with optical frequency domain reflectometry (OFDR). Pt/WO₃ generates local temperature change upon hydrogen exposure, inducing a spectral shift of WFBG with hydrogen concentration changes. Leveraging OFDR's high spatial resolution, it achieves simultaneous spatial localization and spectral demodulation of identical WFBGs without crosstalk, overcoming scalability limits of conventional hydrogen sensors. Experimental results show that the hydrogen sensing scale, density, sensitivity and response time are 5,000 points, 20 mm, 0.365 nm/% and 10 s, respectively. And the sensor has good repeatability, selectivity and in-situ temperature compensation capability. The proposed large-scale and high-density hydrogen sensor provides a scalable solution for leakage monitoring of hydrogen storage facilities and pipeline transportation.