Mie-excitons: understanding strong coupling in dielectric nanoparticles

TL;DR

This paper provides a theoretical analysis of strong coupling between excitons and Mie resonances in dielectric nanoparticles, revealing tunable optical modes with potential for nanophotonics applications.

Contribution

It introduces a detailed analytic framework for understanding Mie-exciton hybrid modes in dielectric nanoparticles, highlighting their tunability and low-loss advantages.

Findings

Large anticrossings in optical spectra demonstrate strong coupling.

Spectral decomposition reveals magnetic-excitonic mode contributions.

Low silicon losses enable observable Rabi oscillations.

Abstract

We theoretically analyse the hybrid Mie-exciton optical modes arising from the strong coupling of excitons in organic dyes or transition-metal dichalcogenides with the Mie resonances of high-index dielectric nanoparticles. Detailed analytic calculations show that silicon--exciton core--shell nanoparticles are characterised by a richness of optical modes which can be tuned through nanoparticle dimensions to produce large anticrossings in the visible or near infrared, comparable to those obtained in plexcitonics. The complex magnetic-excitonic nature of these modes is understood through spectral decomposition into Mie-coefficient contributions, complemented by electric and magnetic near-field profiles. In the frequency range of interest, absorptive losses in silicon are sufficiently low to allow observation of several periods of Rabi oscillations in strongly coupled emitter-particle architectures, as confirmed here by discontinuous Galerkin time-domain calculations for the electromagnetic field beat patterns. These results suggest that Mie resonances in high-index dielectrics are promising alternatives for plasmons in strong-coupling applications in nanophotonics, while the coupling of magnetic and electric modes opens intriguing possibilities for external control.