Resonant tunneling of light through thin metal films via strongly localized surface plasmons

We present a theoretical model of the optical response of a silver film having narrow-grooved zero-order gratings on both sides. It is found that incident p-polarized photons can resonantly tunnel through such a metal film via exciting standing-wave surface plasmon-polariton ~SPP! modes localized in the grooves of the two opposite surfaces. This leads to strong transmission peaks in the visible and ultraviolet regions, while for s-polarized photons the film acts as a nearly perfect mirror. A flat silver surface is almost a perfect reflector for electromagnetic waves in the visible region, and its application as a mirror has a long history. The optical response of a silver surface can be easily understood by examining its dielectric function, which, as a good approximation, can be described by the Drude model e~v!511 itv p 2