Tunable hyperbolic metamaterial cavity towards few exciton strong coupling

TL;DR

This paper theoretically demonstrates that hyperbolic metamaterial cavities can achieve strong coupling with molecular excitons, with tunable parameters allowing for invariant resonance frequency and consistent strong coupling thresholds.

Contribution

It introduces a tunable hyperbolic metamaterial cavity design that enables strong exciton coupling with controllable resonance properties.

Findings

Strong coupling between excitons and whispering gallery modes achieved.

Mode volume can be highly localized within dielectric layers.

Threshold number of excitons for strong coupling remains approximately four.

Abstract

We theoretically investigate coupling interaction between molecule excitons and whispering gallery modes (WGMs) that approaches the limit of single exciton strong coupling in hyperbolic metamaterial (HMM) cavity, composed of a dielectric core wrapped by several stacks of alternative layers of metal and dielectric. We demonstrate that associated with the excitation of the whispering gallery mode, the electric fields with resonance wavelengths that are much larger than the cavity size can be highly localized within a dielectric layer, leading to extremely small mode volumes. By using temporal coupled mode theory to model the interaction in the proposed WGMs-exciton system, we are able to demonstrate that the coupling between molecular excitons and hyperbolic cavity WGMs can reach the strong coupling regime. Furthermore, we also prove that changing both the thickness of inner core and outermost layer can lead to invariant resonance frequency while the threshold number of coupled excitons to fulfill the criteria for strong coupling remains ~ 4 in various sets of tunable HMM cavities.