An integrated optic hydrogen sensor based on SPR on palladium

A small and efficient hydrogen sensor using surface plasmon resonance in an integrated optical waveguide is reported. The waveguide properties are influenced by a thin palladium layer whose optical constants depend on concentration of hydrogen in surrounding gaseous medium. A modal analysis of the sensor structure is performed and a simple sensor model is proposed. Finally, experimental results are presented; detection of hydrogen concentration as low as 4% is demonstrated.