Nonlinear emission dynamics of a GaAs microcavity with embedded quantum wells

TL;DR

This study investigates the nonlinear emission dynamics of a GaAs microcavity with embedded quantum wells, revealing how excitation density and additional illumination influence polariton decay times and relaxation processes.

Contribution

It provides new insights into how polariton decay times depend on wavevector and excitation conditions, highlighting the roles of scattering processes at large negative detunings.

Findings

Decay time increases with wavevector at high excitation densities

Additional nonresonant illumination enhances emission intensity significantly

Polariton-polariton and polariton-free carrier scattering dominate relaxation near the lower polariton branch

Abstract

The emission dynamics of a GaAs microcavity at different angles of observation with respect to the sample normal under conditions of nonresonant picosecond-pulse excitation is measured. At sufficiently high excitation densities, the decay time of the lower-polariton emission increases with the polariton wavevector; at low excitation densities the decay time is independent of the wavevector. The effect of additional nonresonant continuous illumination on the emission originating from the bottom of the lower polariton branch is investigated. The additional illumination leads to a substantial increase in the emission intensity (considerably larger than the intensity of the photoluminescence excited by this illumination alone). This fact is explained in terms of acceleration of the polariton relaxation to the radiative states due to scattering by charge carriers created by the additional illumination. The results obtained show, that at large negative detunings between the photon and exciton modes, polariton-polariton and polariton-free carrier scattering are the main processes responsible for the filling of states near the bottom of the lower polariton branch.