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Extraordinary optical transmission with tapered slits: effect of higher diffraction and slit resonance orders

Abstract:

Transmission through thin metal films with a periodic arrangement of tapered slits is considered. Transmission maps covering a wide range of periods, film thicknesses, and taper angles are presented. The maps show resonant transmission when fundamental and higher-order slit resonances are excited. A study of the effect on transmission of different combinations of available transmission and reflection diffraction orders show optimum total transmission when only the fundamental reflection order and higher transmission diffraction orders are available. The optimum taper angle is shown to be in the range of 6°–10°. Both theory and experiments show split-peak spectra and shifted-peak spectra due to interference between a slit resonance and Rayleigh–Wood anomalies.