Time-domain analysis of mechanism of plasmon-assisted extraordinary optical transmission

We present the time-domain analysis of the extraordinary optical transmission of the slits milled on the thin metallic film. We employ the finite-difference time-domain method to study the variations of the transmission energies with the sampling time received by several monitors that are placed on the specified positions in the structure. It is found that the physical origin of the related phenomenon may be contributed by a combining effect of single-slit effect and interslits effect. The single-slit effect is brought by the excitation of surface-plasmon polaritons from the isolated slit and the interslits effect is caused by phase interference of the transmitted waves from two slits. When the transmissivity of an isolated slit is adjusted to a maximum, total transmissivity of the grating is never governed by phase interference and can be qualified to the contribution from a single slit alone.