Design and simulation of a fiber-optic hydrogen sensor based on tunable diode laser spectroscopy

A fiber-optic hydrogen sensor based on tunable diode laser spectroscopy is designed. The fiber-optic hydrogen sensor is composed of a fiber-optic Fabry-Perot interferometer, where one mirror is made of a hydrogen sensitive Pd thin film. By optimizing the structure parameters of the fiber-optic hydrogen sensor, a reflectance spectrum with the similar curve to a gas absorption spectrum is obtained. The reflectance spectrum of the fiber-optic hydrogen sensor is calculated at different hydrogen concentrations and the relation between the intensity minimums of the spectrum and the hydrogen concentrations is explored. The wavelength modulation spectroscopy is used to analyze the reflectance spectra, the relation between the second harmonic component and hydrogen concentrations is obtained, and the feasibility of the application of TDLAS on the fiber-optic hydrogen sensor is verified. This hydrogen sensing method has great potential in industrial application due to the advantages of high sensitivity, low cost, system's simplicity.