Surface-Plasmon-Enhanced Optical Transmission through Planar Metal Films

Abstract

We have studied the optical transmission properties of planar metallic films closely coupled to diffraction gratings and we show here that this can give rise to plasmon-enhanced transmission. The coupling between two optically excited surface plasmon (SP) modes on opposite interfaces of the metal film gives rise to a high-transmission feature in the spectral transmittance. The overall transmission is a result of the coupling between the incident light and the SP modes, as well as waveguide modes in the dielectric spacer between the diffraction grating and the planar metal film. The spectral locations of the transmission peaks agree well with rigorous coupled wave analysis (RCWA) calculations.