Scattering of infrared light by dielectric core-shell particles

TL;DR

This paper investigates how infrared light scatters off dielectric core-shell particles, revealing complex resonant behaviors and energy dissipation patterns influenced by the core-shell structure.

Contribution

It provides a detailed analysis of resonant scattering phenomena in dielectric core-shell particles, highlighting the roles of surface charge interactions and energy dissipation.

Findings

Resonance series linked to surface charge modes at interfaces.

Identification of bonding and antibonding resonance behaviors.

Complex energy dissipation patterns within the particle.

Abstract

We study the scattering of infrared light by small dielectric core-shell particles taking a sapphire sphere with a CaO core as an example. The extinction efficiency of such a particle shows two intense series of resonances attached, respectively, to in-phase and out-of-phase multipolar polarization-induced surface charges build-up, respectively, at the core-shell and the shell-vacuum interface. Both series, the character of the former may be labelled bonding and the character of the latter antibonding, give rise to anomalous scattering. For a given particle radius and filling factor the Poynting vector field shows therefore around two wave numbers the complex topology of this type of light scattering. Inside the particle the topology depends on the character of the resonance. The dissipation of energy inside the particle also reflects the core-shell structure. It depends on the resonance and shows strong spatial variations.