Signature of the microcavity exciton-polariton relaxation mechanism in the polarization of emitted light

TL;DR

This study investigates how exciton-polariton condensates relax into their ground state and how their polarization properties reflect these relaxation mechanisms, using spin-dependent spectroscopy under different pumping schemes.

Contribution

It provides experimental evidence linking the polarization of emitted light to the relaxation mechanisms in exciton-polariton condensates, highlighting the role of phonon and polariton-polariton scattering.

Findings

Relaxation involves multiple phonon and one polariton-polariton scattering events.

Linearly polarized pump results align with spin-dependent Boltzmann models.

Circular pump shows a bottleneck effect indicating inefficient relaxation.

Abstract

We have performed real and momentum space spin-dependent spectroscopy of spontaneously formed exciton polariton condensates for a non-resonant pumping scheme. Under linearly polarized pump, our results can be understood in terms of spin-dependent Boltzmann equations in a two-state model. This suggests that relaxation into the ground state occurs after multiple phonon scattering events and only one polariton-polariton scattering. For the circular pumping case, in which only excitons of one spin are injected, a bottleneck effect is observed, implying inefficient relaxation.