Ultra-high sensitive optical fiber hydrogen sensor using self-referenced demodulation method and WO_3-Pd_2Pt-Pt composite film

Abstract

A novel fiber optic hydrogen concentration detection platform with significantly enhanced performance is proposed and demonstrated in this paper. The hydrogen sensing probe was prepared by depositing WO₃-Pd₂Pt-Pt composite film on the fiber tip of two Bragg gratings paired with high-low reflectivity. At a room temperature of 25°C, the hydrogen sensor has a significant response towards 10 ppm hydrogen in nitrogen atmosphere, and may detect tens of ppb hydrogen changes when the hydrogen concentration is between 10~60 ppm. Besides, the proposed system shows quick response when the hydrogen concentration is above 40 ppm. Moreover, the hydrogen sensor shows good repeatability during the hydrogen response. This work proposes a new concept to develop hydrogen sensing technology with ultra-high sensitivity, which can significantly promote its potential application in various fields, especially for ultra-low hydrogen detection in oxygen-free environment.