Plasmonic interactions between a perforated gold film and a thin gold film

Based on the finite difference time domain method, we investigated theoretically the optical properties and the plasmonic interactions between a gold film perforated with periodic sub-wavelength holes and a thin gold film. We showed that the plasmon resonant energies and intensities depend strongly on the thicknesses of the two films and the lattice constant. Based on the distributions of normal electric field component E_z, tangential electric field component E_y and total energy, we showed that the optical transmission is due to the collaboration of the localized waveguide resonance, the surface plasmon resonance and the coupling of the flat-surface plasmon of the two layers.