Improved performance of fiber optic hydrogen sensor based on controllable optical heating technology

• Jixiang Dai, Kai Yin, Zhangning Chen, Wenbin Hu, Minghong Yang, Jinghua Fu, Xuxu Sun, and Xianfeng Chen
• received 02/26/2024; accepted 04/29/2024; posted 04/30/2024; Doc. ID 522375
• Abstract: A novel and compact fiber optic hydrogen sensor based on light intensity demodulation and controllable optical heating technology is proposed and experimentally investigated. This system employs three photodetectors for optic signal transformation. The first PD is used to receive a little fraction of amplified spontaneous emission (ASE) for calibration, and the second PD is utilized to detect optic signal reflected by single mode fiber deposited with WO3-Pd2Pt-Pt composite film. The last PD is utilized to receive optical power reflected by short fiber Bragg grating (SFBG) with central wavelength located in steep wavelength range (the intensity decreases approximately linearly with increase of wavelength) of ASE light source. A 980 nm laser and proportion integration differentiation (PID) controller were employed to ensure the hydrogen sensitive film working at operating temperature of 60°C. This sensing system can display a quick response time of 0.4 s towards 10000 ppm hydrogen in air. In addition, detection limit of 5 ppm in air can be achieved with this sensing system. The stability of this sensor can be greatly enhanced with controllable optical heating system, which can greatly promote its potential application in various fields.