Many different types of fiber optic hydrogen gas sensors have been used to detect hydrogen concentration. Almost invariably these sensors, as well as the electrical hydrogen sensors, use palladium as the gas-sensitive layer by detecting its electrical and optical properties change, when it exposed to hydrogen. However the sensibility of them is poor and the minimum hydrogen detecting level is still very high. Fiber Bragg gratings (FBG) control over the properties of light propagating within the fiber. A change of the effective refractive index of grating period caused by the surrounding environment will cause a shift in the reflective Bragg wavelength. The totally different principle makes FBG with good sensing characters. In addition, FBG has a built-in self-referencing capability and can be multiplexed along a single fiber. Here a new method is put forward to detect the hydrogen concentration by FBG. The working principle of FBG hydrogen sensor is based on surface plasmon resonance. Fiber is firstly side polished in the FBG region to enable evanescent wave interaction. Experiment showed that this method is very sensitive, as low as 0.1% (1000ppm) of hydrogen concentration can be detected and the response time is less then 5 seconds.

Date Published: 28 October 2009
PDF: 7 pages
Proc. SPIE 7514, Photonics and Optoelectronics Meetings (POEM) 2009: Fiber Optic Communication and Sensors, 75140K (28 October 2009); doi: 10.1117/12.845095

Published in SPIE Proceedings Vol. 7514:
Photonics and Optoelectronics Meetings (POEM) 2009: Fiber Optic Communication and Sensors
Dieter Stefan Jäger; Hequan Wu; Shuisheng Jian; Desheng Jiang; Deming Liu; Weiwei Dong; Qizhen Sun; Xiaochun Xiao, Editor(s)