Fiber optic Bragg grating sensors for hydrogen gas sensing

Boonsong Sutapun; Massood Tabib-Azar; Alex A. Kazemi

doi:10.1117/12.347817

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7 May 1999 Fiber optic Bragg grating sensors for hydrogen gas sensing

Boonsong Sutapun, Massood Tabib-Azar, Alex A. Kazemi

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Proceedings Volume 3740, Optical Engineering for Sensing and Nanotechnology (ICOSN '99); (1999) https://doi.org/10.1117/12.347817
Event: Optical Engineering for Sensing and Nanotechnology (ICOSN '99), 1999, Yokohama, Japan

Abstract

We report a new type of optical hydrogen sensor with a fiber optic Bragg grating (FBG) coated with palladium. The sensing mechanism in this device is based on the mechanical stress that is induced in the palladium coating when it absorbs hydrogen. The stress in the palladium coating stretches and shifts the Bragg wavelength of the FBG. Using FBGs with different wavelengths many such hydrogen sensor can be multiplexed on a single optical fiber. Operation of two multiplexing sensors is demonstrated. Moreover, hydrogen and thermal sensitivities of the senors were measured and calculated using a simple elastic model. Moreover, to quantify the amount of stress in the palladium film as a function of hydrogen concentration, a novel and very sensitive method was devised and used to detect deflections in a Pd-coated cantilever using an evanescent microwave probe. This stress was in the range of 5.26 - 8.59 X 10⁷ Pa for H₂ concentrations of 0.5 - 1.4% at room temperature, which is about three times larger than that found in the bulk palladium for the same range of H₂ concentrations.

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Boonsong Sutapun, Massood Tabib-Azar, and Alex A. Kazemi "Fiber optic Bragg grating sensors for hydrogen gas sensing", Proc. SPIE 3740, Optical Engineering for Sensing and Nanotechnology (ICOSN '99), (7 May 1999); https://doi.org/10.1117/12.347817

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