Decomposing the scattered field of two-dimensional metaatoms into multipole contributions

TL;DR

This paper presents a method to decompose the near-field scattering of 2D metaatoms into multipole contributions using cylindrical harmonics, aiding metamaterial design by identifying key multipole effects.

Contribution

A novel technique that relates cylindrical harmonic expansion to Cartesian multipoles for analyzing scattered fields of 2D metaatoms.

Findings

Enables identification of electric and magnetic multipoles in scattered fields

Facilitates distinction between arrangement effects and design effects in metamaterials

Provides a tool for targeted metamaterial engineering

Abstract

We introduce a technique to decompose the scattered near field of two-dimensional arbitrary metaatoms into its multipole contributions. To this end we expand the scattered field upon plane wave illumination into cylindrical harmonics as known from Mie theory. By relating these cylin- drical harmonics to the field radiated by Cartesian multipoles, the contribution of the lowest order electric and magnetic multipoles can be identified. Revealing these multipoles is essential for the design of metamaterials because they largely determine the character of light propagation. In par- ticular, having this information at hand it is straightforward to distinguish between effects that result either from the arrangement of the metaatoms or from their particular design.