Plasmonic sensing of hydrogen in Pd nano-hole arrays

The optical properties in visible – near infrared range of Pd nano-hole arrays (PNA) and Pd thin films under hydrogen absorption – desorption processes have been investigated. The PNA samples show plasmonic resonances with about three times more transmission than that of the Pd thin film samples with a similar thickness. Remarkably, due to the plasmonic effect the PNA samples exhibit two times larger transmission change, normalized to the Pd cover area, under the hydrogen absorption/desorption processes at the Wood’s anomaly positions. The PNA sample can be used as a hydrogen sensor that has a better signal-to-noise ratio than the one based on the corresponding Pd thin film. The experimental results are confirmed by the finite-difference time domain (FDTD) calculations.