Extraordinary optical transmission properties of a novel Bi-layered plasmonic nanostructure array

The optical transmission properties of a novel bi-layer plasmonic nanostructure array (BPNA), consisting of an array of gold nanoholes, glass and an array of gold nanodisks, was investigated by the finite element method. A well-defined localized surface plasmon (LSP) resonance peak appeared in the transmission spectra due to the coupling between the LSP of the metal nanoholes and the LSP of the nanodisks. The position and the intensity of the coupled LSP resonance peak depended strongly on the distance between the nanohole and the nanodisk arrays, the diameters of the arrays and the thickness of the nanohole or nanodisk arrays. The coupled LSP resonance peak exhibited a higher figure of merit compared to that for either the nanohole array or the nanodisk array. Results indicated that the bi-layer nanodevice was a highly sensitive detector for tunable plasmas, and should aid in better understanding of the mechanisms for extraordinary optical transmission phenomena.