Hybridization and the origin of the Fano resonances in symmetric nanoparticle trimers

TL;DR

This paper introduces a simplified hybridization model to analyze Fano resonances in symmetric plasmonic and dielectric nanoparticle trimers, supported by analytical derivations, simulations, and the first experimental measurements.

Contribution

A new simplified hybridization approach is developed to analytically derive eigenmodes and Fano resonances in symmetric nanoparticle trimers, applicable to both plasmonic and dielectric systems.

Findings

Accurately reproduces full wave simulations of Fano resonances.

Identifies modal interference mechanisms in plasmonic trimers.

Demonstrates polarization-independent Fano resonances in dielectric trimers with experimental validation.

Abstract

We study the light scattering by plasmonic and dielectric symmetric trimers to investigate the existence of polarization-independent Fano resonances. Plasmonic hybridization theory is revealed to hide simple physics, and we instead provide a simplified model for hybridization to derive a plasmonic trimer's eigenmodes analytically. This approach is demonstrated to accurately recreate full wave simulations of plasmonic trimers and their Fano resonances. We are subsequently able to deduce the grounds for modal interference in plasmonic trimers and the related formation of Fano resonances. However, by taking advantage of the generality of our simplified hybridization approach, we are also able to investigate the eigenmodes of all-dielectric trimers. We show that bianisotropic coupling channels between high-index dielectric nanoparticles are able to increase the capacity for Fano resonances, even at normal incidence. We finally provide the first experimental measurements of sharp, polarization-independent Fano resonances from a symmetric all-dielectric trimer, with very good agreement to the predicted response from our simplified hybridization theory.