Scattering in Multilayered Structures: Diffraction from a Nanohole

TL;DR

This paper introduces a semi-analytical method to compute the angular spectrum of scattered fields from nanoholes in multilayered structures using Green's tensor expansion and orthogonal vector wave functions.

Contribution

It develops a novel technique to find expansion coefficients of scattered fields in multilayered media, applicable to various geometries including spherical and cylindrical layers.

Findings

Successfully applied to nanoholes in metallic films under Gaussian illumination.

Provides a flexible formalism extendable to spherical and cylindrical multilayered media.

Offers a semi-analytical approach combining Green's tensor spectral expansion with orthogonal vector wave functions.

Abstract

The spectral expansion of the Green's tensor for a planar multilayered structure allows us to semi analytically obtain the angular spectrum representation of the field scattered by an arbitrary dielectric perturbation present in the structure. In this paper we present a method to find the expansion coefficients of the scattered field, given that the electric field inside the perturbation is available. The method uses a complete set of orthogonal vector wave functions to solve the structure's vector wave equation. In the two semi-infinite bottom and top media, those vector wave functions coincide with the plane-wave basis vectors, including both propagating and evanescent components. The technique is used to obtain the complete angular spectrum of the field scattered by a nanohole in a metallic film under Gaussian illumination. We also show how the obtained formalism can easily be extended to spherically and cylindrically multilayered media. In those cases, the expansion coefficients would multiply the spherical and cylindrical vector wave functions.