FBG Hydrogen Sensor Based on Pd₈₇–Ni₁₃/Pd₄–Ag₁ Thin Film and Femtosecond Laser Ablation

Abstract

A novel laser machined spiral microstructure fiber Bragg grating (FBG) hydrogen sensor and coated with composite sensing film is presented. The sensor probes are sputtered with Pd/Ni and Pd/Ag film, respectively. Experimental results exhibit that a pitch 60 μm FBG with double spiral microstructures, coated with 520 nm Pd/Ni and Pd/Ag film has hydrogen gas sensitivity in air of 13 pm/%H and 25 pm/%H, respectively. The laser-ablated spiral microstructured probes with composite films shown greater sensitivity compared with standard FBG probes with similar coating. The optimum testing temperature (50 °C) enhanced the sensitivity and repeatability of the probes.

Keywords:

• Femtosecond laser
• hydrogen gas sensor
• spiral microgroove
• fiber Bragg grating
• Pd–Ni
• Pd/Ag

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under grant 51975192, 51975442, the Natural Science Foundation of Hubei Province under grant 2019CFB632, and the Ph.D. Research Fund of Hubei University of Arts and Science (No. 2059016), Hubei Superior and Distinctive Discipline Group of “Mechatronics and Automobiles” (XKQ2021050).