Abstract
Optical transmission through multi-layered systems of corrugated metallic thin films is investigated by rigorous electromagnetic simulations based on an exact Green tensor method. Compared to a single metal slab of equivalent thickness and volume, it was found that the multi-layered system can significantly impede the field decay, often leading to transmission greater than that expected from the Fabry-Perot resonance-like behavior exhibited by subwavelength slits in a single slab. Extraordinary optical transmission is also observable for systems of layers whose combined thicknesses are much greater than the skin depth of the metal. Structures consisting of up to five layers with a net thickness of 500 nm for the metal films were considered in our study. These findings demonstrate that an appreciable fraction of the optical power that is incident on the thin metal films can be transmitted over distances greater than their skin depth using plasmonic resonances.
Highlights
Extraordinary optical transmission (EOT) through corrugated thin metal films and subwavelength-aperture arrays in metal plates has evoked great interest since its first experimental demonstration by Ebbesen et al [1]
To strengthen our claim that surface plasmons are responsible for these enhanced field effects, we performed another series of simulations with more plasmon pits on each of the layers, keeping the same incident Gaussian beam as before
We consider if the same effects can be achieved with perforated slits instead of plasmon pits, since the former is perceivably a simpler structure to implement in practice
Summary
Extraordinary optical transmission (EOT) through corrugated thin metal films and subwavelength-aperture arrays in metal plates has evoked great interest since its first experimental demonstration by Ebbesen et al [1]. We show that corrugated metallic films arranged in cascade can potentially impede the exponential decay of electromagnetic fields that is otherwise characteristic of optically thick metal slabs. The geometry of the layered structures considered in the present study is motivated by previous investigations on achieving plasmon-assisted super-resolution in near field optical readout systems [18, 17].
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