Modelling of Palladium Gold alloy- dielectric stratified loaded plasmonic waveguide for hydrogen detection at room temperature

Abstract

A plasmonic waveguide loaded with metal - dielectric stratified layer is reported for room temperature hydrogen sensing. Pd-Au alloy with atomic ratio 3:1 (Pd/Au) is used as the metal and air is used as dielectric layer in the sensor. When hydrogen is loaded in the waveguide the alloy absorbs hydrogen and the effective permittivity of the stratified medium changes. Density functional theory and Bruggeman's effective medium theory are used to calculate the permittivity of bare and hydrogenated alloy. At a specific wavelength the change in the absorption loss of the device on hydrogen absorption is used as the measurement for hydrogen detection. At 633 nm the loss decreases almost linearly with increasing hydrogen concentration. For a device length of 10 μm the change of loss is achieved about 0.03 dB for 1% change of hydrogen concentration.