Optical transmission of planar metallic films coated by two-dimensional colloidal crystals

Optical transmissions through a continuous planar metal film (without holes) with two-dimensional colloidal crystals coated on one or both interfaces have been experimentally and numerically investigated. Enhanced optical transmissions in the near-infrared regime can be observed for the metal film with identical two-dimensional colloidal crystals coated on both sides, which occur due to the resonant tunneling of surface polariton Bloch eigenmodes excited on periodically structured interfaces. Numerical simulations of transmission spectra show an excellent agreement with the measured ones. Additionally, the numerical simulations reveal that the intensity of tunneling transmission is strongly dependent on the relative shift of the two-dimensional colloidal crystals on the opposite interfaces of the metallic film.