Exciton spin relaxation in InAs/InGaAlAs/InP(001) quantum dashes emitting near 1.55 {\mu}m

TL;DR

This study examines exciton spin relaxation and optical polarization in InAs/InGaAlAs/InP quantum dashes emitting near 1.55 μm, revealing how optical spin pumping and intrinsic asymmetries affect spin polarization and memory at cryogenic temperatures.

Contribution

It demonstrates a spin pumping scheme using LO-phonon-mediated scattering that achieves over 50% polarization, highlighting the role of asymmetries in spin dynamics.

Findings

Spin polarization exceeds 50% with specific optical pumping.

Intrinsic asymmetries influence polarization degree and dynamics.

Coherent scattering processes are key to spin control.

Abstract

Exciton spin and related optical polarization in self-assembled InAs/In$_{0.53}$Ga$_{0.23}$Al$_{0.24}$As/InP(001) quantum dashes emitting at 1.55 {\mu}m are investigated by means of polarization- and time-resolved photoluminescence, as well as photoluminescence excitation spectroscopy, at cryogenic temperature. We investigate the influence of highly non-resonant and quasi-resonant optical spin pumping conditions on spin polarization and spin memory of the quantum dash ground state. We show that a spin pumping scheme, utilizing the longitudinal-optical-phonon-mediated coherent scattering process, can lead to the polarization degree above 50%. We discuss the role of intrinsic asymmetries in the quantum dash that influence values of the degree of polarization and its time evolution.