From Strong to Weak Coupling Regime in a Single GaN Microwire up to Room Temperature

TL;DR

This paper demonstrates that GaN microwires can achieve strong exciton-photon coupling up to room temperature with a large Rabi splitting, using a simple method that does not require prior knowledge of photonic modes.

Contribution

The study introduces a novel method to demonstrate strong coupling in GaN microwires without prior mode knowledge and confirms free excitons as the oscillator source.

Findings

Achieved Rabi splitting of 125 meV at room temperature.

Rabi splitting to linewidth ratio of 15.

Simpler fabrication compared to planar microcavities.

Abstract

Large bandgap semiconductor microwires constitute a very advantageous alternative to planar microcavities in the context of room temperature strong coupling regime between exciton and light. In this work we demonstrate that in a GaN microwire, the strong coupling regime is achieved up to room temperature with a large Rabi splitting of 125 meV never achieved before in a Nitride-based photonic nanostructure. The demonstration relies on a method which doesn't require any knowledge \'a priori on the photonic eigenmodes energy in the microwire, i.e. the details of the microwire cross-section shape. Moreover, using a heavily doped segment within the same microwire, we confirm experimentally that free excitons provide the oscillator strength for this strong coupling regime. The measured Rabi splitting to linewidth ratio of 15 matches state of the art planar Nitride-based microcavities, in spite of a much simpler design and a less demanding fabrication process. These results show that GaN microwires constitute a simpler and promising system to achieve electrically pumped lasing in the strong coupling regime.