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

Optical and Quantum Electronics (Impact Factor: 1.08). 41(5):409-427. DOI: 10.1007/s11082-010-9366-2

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

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    ABSTRACT: By numerically calculating the relevant electromagnetic fields and charge current densities, we show how local charges and currents near subwavelength structures govern light transmission through subwavelength apertures in a real metal film. The illumination of a single aperture generates surface waves; and in the case of slits, generates them with high efficiency and with a phase close to -π with respect to a reference standing wave established at the metal film front facet. This phase shift is due to the direction of induced charge currents running within the slit walls. The surface waves on the entrance facet interfere with the standing wave. This interference controls the profile of the transmission through slit pairs as a function of their separation. We compare the calculated transmission profile for a two-slit array to simple interference models and measurements [Phys. Rev. B 77(11), 115411 (2008)].
    Optics Express 08/2011; 19(17):16139-53. · 3.55 Impact Factor