Interaction of light with subwavelength apertures: a comparison of approximate and rigorous approaches

Abstract

The interaction of an electromagnetic wave with various classes of subwavelength one dimensional apertures is studied in detail,
using several approximate and rigorous approaches. The attention is given to a comparison of the revealing basic physical
features of the interaction. Several semi-analytical models which are able to predict the enhanced transmission phenomenon
are reviewed, applied, and extended: the one-mode periodic model, the model based on the composite diffracted evanescent wave
approach, and the so called combined model. Then, a detailed rigorous modeling is performed, using the finite difference time
domain method, to study the parametrical dependencies of all critical parameters (i.e. the parameters of the aperture—diameter
and thickness, and also the parameters of the surrounding corrugations). The transmission properties of the subwavelength
single apertures and apertures with the supporting corrugations on the input side and on both sides of the structure are compared
in detail, and the options for their optimizations are discussed. Finally, the results of approximate models are compared
with that from the rigorous finite difference time domain modeling, for the case of two important cases, a periodic array
of slits and the slit-groove diffraction problem, i.e. a combination of the aperture and one corrugation.

KeywordsSubwavelength aperture-Surface plasmons-Numerical modeling-Finite difference time domain method-Diffracted evanescent wave model