Dispersion Relation of Bloch Modes in Corrugated Metallic Thin Film With Square-Lattice Nanowell Array

The optical properties of plasmonic crystal consisting of corrugated metallic thin film with square-lattice nanowell array are theoretically investigated. The dispersion relationship and mode behaviors of surface plasmon polariton (SPP) Bloch modes around the Γ point in the first Brillouin zone are calculated using rigorous coupled wave analysis method. We found that these properties are relevant to the Bloch-mode excitation of the top surface of metal layer by free-space illumination. We have also studied the influence of the patterned silicon substrate on the excitation of SPP Bloch mode and found that with the increase of gold film thickness, the proportion of energy coupling to the silicon substrate becomes smaller, which would increase the coupling efficiency of SPP mode.