Relaxation and emission of Bragg-mode and cavity-mode polaritons in a ZnO microcavity at room temperature

TL;DR

This study investigates strong coupling and polariton relaxation in a ZnO microcavity at room temperature, revealing a relaxation bottleneck that can be mitigated by high excitation density, leading to dominant Bragg-mode polariton emission.

Contribution

It demonstrates simultaneous strong coupling of excitons to both cavity and Bragg modes in a ZnO microcavity at room temperature, and analyzes polariton relaxation dynamics.

Findings

Strong coupling of excitons to cavity and Bragg modes at room temperature.

Identification of a relaxation bottleneck in Bragg-mode polaritons.

High excitation density can overcome the relaxation bottleneck.

Abstract

The strong coupling regime in a ZnO microcavity is investigated through room temperature photoluminescence and reflectivity experiments. The simultaneous strong coupling of excitons to the cavity mode and the first Bragg mode is demonstrated at room temperature. The polariton relaxation is followed as a function of the excitation density. A relaxation bottleneck is evidenced in the Bragg-mode polariton branch. It is partly broken under strong excitation density, so that the emission from this branch dominates the one from cavity-mode polaritons.