An effective cavity resonance model for enhanced optical transmission through arrays of subwavelength apertures in metal films

TL;DR

This paper introduces a cavity resonance model that accurately predicts enhanced optical transmission through subwavelength aperture arrays in metal films, explaining the physical mechanism and geometric dependencies.

Contribution

A novel cavity resonance model for subwavelength aperture transmission that analytically predicts transmission peaks and their dependence on geometry.

Findings

Model accurately predicts transmission peak frequencies.

Explains the dependence of peaks on aperture geometry.

Shows strong correlation with simulations and prior results.

Abstract

We present a novel theoretical approach for modeling the resonant properties of transmission through subwavelength apertures penetrating metal films. We show that cavity mode theory applies to an effective resonant cavity whose dimensions are determined by the aperture's geometry and the evanescent decay lengths of the associated diffracted waves. This method suggests a concrete physical mechanism for the enhanced transmission observed in periodic aperture arrays, namely it is the evanescently scattered light, localized in the near field of metal surface, which couples into the apertures. Furthermore, it analytically predicts the frequencies of peaks in enhanced transmission, the quality factor of the peaks, and explains their dependence on variation in the hole radius, periodicity, and the film thickness over a wide range of geometries. This model demonstrates strong correlation to simulation and existing results with a high degree of accuracy.