Surface mode hybridization in the optical response of core-shell particles

TL;DR

This paper provides an exact analytical reformulation of Mie scattering coefficients for core-shell particles, revealing their surface mode hybridization across all sizes and multipole orders, extending previous electrostatic approximations.

Contribution

It introduces a novel exact rewriting of Mie coefficients that enables interpretation of scattering in terms of surface mode hybridization for arbitrarily sized core-shell particles.

Findings

Analytical hybridization scenario derived for all multipole orders.

Reformulation applicable to stratified spheres.

Enhanced understanding of optical responses in core-shell particles.

Abstract

We present an exact rewriting of the Mie coefficients describing the scattering of light by a spherical core-shell particle which enables their interpretation in terms of an hybridization of the two surface modes arising, respectively, at the core-shell and the shell-medium interface. For this particular case we thus obtain from the Mie theory--analytically for all multipole orders and hence for arbitrarily sized particles--the hybridization scenario, which so far has been employed primarily for small particles in the electrostatic approximation. To demonstrate the strength of the rewriting approach we also extract the hybridization scenario for a stratified sphere directly from the expansion coefficients for the electromagnetic fields.