Bistability and nonequilibrium transitions in the optically polarized system of cavity polaritons under nanosecond-long resonant excitation

TL;DR

This study investigates the polarization-dependent nonequilibrium transitions and bistability in cavity polaritons under nanosecond-long resonant excitation, revealing dynamics that require an extended model including an unpolarized exciton reservoir.

Contribution

It introduces a modified theoretical model accounting for an unpolarized exciton reservoir to explain polarization instability and bistability in cavity polaritons under resonant excitation.

Findings

Sharp threshold-like changes in polarization and intensity observed

Conventional models are insufficient to explain the dynamics

Unpolarized exciton reservoir is essential for accurate modeling

Abstract

The polarization dependence of nonequilibrium transitions in a multistable cavity-polariton system is studied under a nanosecond long resonant optical excitation at the normal and magic angle incidences with various polarizations of the pump beam. The temporal correlations between the frequency, intensity, and optical polarization of the intra-cavity field, which all undergo sharp threshold-like changes due to the spin dependent interaction of cavity polaritons, are visualized. The observed dynamics cannot be reproduced within the conventional semi-classical model based on the Gross-Pitaevskii equations. To explain the observed phenomena, it is necessary to take into account the unpolarized exciton reservoir which brings on additional blueshift of bright excitons, equal in the $\sigma^+$ and $\sigma^-$ polarization components. This model explains the effect of polarization instability under both pulsed and continuous wave resonant excitation conditions, consistently with the spin ring pattern formation that has recently been observed under Gaussian shaped excitation.