Polarization Control of the Non-linear Emission on Semiconductor Microcavities

TL;DR

This paper demonstrates how the circular polarization of non-linear emission in semiconductor microcavities can be controlled via exciton-cavity detuning, revealing the role of stimulated scattering and spin level degeneracy lifting.

Contribution

It introduces a method to control emission helicity in microcavities by tuning exciton-cavity detuning, highlighting the impact of stimulated scattering on polarization.

Findings

Large polarization values achieved shortly after pulsed excitation

Polarization sign depends on exciton-cavity detuning

Stimulated scattering influences spin state population

Abstract

The degree of circular polarization ($\wp$) of the non-linear emission in semiconductor microcavities is controlled by changing the exciton-cavity detuning. The polariton relaxation towards \textbf{K} $\sim 0$ cavity-like states is governed by final-state stimulated scattering. The helicity of the emission is selected due to the lifting of the degeneracy of the $\pm 1$ spin levels at \textbf{K} $\sim 0$. At short times after a pulsed excitation $\wp$ reaches very large values, either positive or negative, as a result of stimulated scattering to the spin level of lowest energy ($+1/-1$ spin for positive/negative detuning).