Direct Observation of Whispering Gallery Mode Polaritons and Their Dispersion in a ZnO Tapered Microcavity

TL;DR

This paper demonstrates the direct observation of exciton-photon strong coupling in a ZnO tapered whispering gallery microcavity at room temperature, revealing polariton dispersion and mode transitions through micro-photoluminescence spectroscopy.

Contribution

It provides the first direct measurement of polariton dispersion in a ZnO tapered microcavity, combining experimental observations with a plane wave model to understand exciton-photon interactions.

Findings

Observation of transition from WG modes to excitonic polaritons

Mapping of polariton dispersion in a tapered microcavity

Validation of the plane wave model for exciton-photon coupling

Abstract

We report direct observation of the strong exciton-photon coupling in ZnO tapered whispering gallery (WG) microcavity at room temperature. By scanning excitations along the tapered arm of ZnO tetrapod using micro-photoluminescence spectrometer with different polarizations, we observed a transition from the pure WG optical modes in the weak interaction regime to the excitonic polariton in the strong coupling regime. The experimental observations are well described by using the plane wave model including excitonic polariton dispersion relation. This provides a direct mapping of the polariton dispersion, and thus a comprehensive picture for coupling of different excitons with differently polarized WG modes.