Transmissions through a metallic film at near-infrared wavelengths with different surface corrugations on both sides are systemically studied. The calculations are performed by the three-dimensional finite-different time-domain method. Calculated results show that the transmissions are strongly dependent on the surface structures. Compared with other structures, the transmission for a film periodically drilled by cross air grooves are relatively larger. Transmission is enhanced more with symmetric conditions on both layers than the asymmetric case. The enhanced transmission can be explained by a competition between the absorption in the metal and enhanced transmission due to coupled surface plasmon resonance.
- surface plasmons
- diffraction scattering