Integrated optic sensor for the detection of H2 concentrations

A Mach-Zehnder interferometer has been utilized as a basic optical device for a new hydrogen sensor. The sensitivity to hydrogen is obtained through refractive index changes induced by absorption or desorption of hydrogen in a thin film of palladium deposited on one of the two branches of the interferometer. The relative phase shift of the light propagating along the two branches gives rise to a change in the output intensity, which can be correlated to the hydrogen concentration.