Analytical analysis of the resonance response of subwavelength nanoscale cylindrical apertures in metal at near-ultraviolet, optical, and near-infrared frequencies

In this paper we analytically study the resonance response of cylindrical subwavelength apertures embedded in metal films at near-UV, optical, and near-IR frequencies. This analysis is concise, and allows accurate and intuitive prediction of both propagating and evanescent modes, which are key contributors to enhanced optical transmission through thin metal films. In this approach we do not analyze the detailed behavior of the fields inside the metal walls, but still obtain the effects of the implicit buildup of charges within those walls. We calculate the modal dispersion relation, cutoff dependence on cylinder radius, and waveguide attenuation for a cylindrical aperture embedded in metal. We support our findings with finite element simulations and find strong agreement with our theory.