Spontaneous Polarisation Build up in a Room Temperature Polariton Laser

TL;DR

This paper reports the observation of spontaneous polarization build-up in a room-temperature GaN polariton laser, demonstrating spontaneous symmetry breaking in a Bose-Einstein condensate of exciton-polaritons, with random polarization orientations across pulses.

Contribution

It provides experimental evidence of spontaneous polarization in a room-temperature polariton laser, linking it to symmetry breaking in exciton-polariton condensates, a novel observation in this field.

Findings

Spontaneous vector polarization of ~50% observed

Polarization orientation varies randomly between pulses

Behavior differs from traditional lasers

Abstract

We observe the build up of strong (~50%) spontaneous vector polarisation in emission from a GaN-based polariton laser excited by short optical pulses at room temperature. The Stokes vector of emitted light changes its orientation randomly from one excitation pulse to another, so that the time-integrated polarisation remains zero. This behaviour is completely different to any previous laser. We interpret this observation in terms of the spontaneous symmetry breaking in a Bose-Einstein condensate of exciton-polaritons.