Exciton spin relaxation in InAs/InGaAlAs/InP(001) quantum dashes emitting near 1.55μm

Exciton spin and related optical polarization in self-assembled InAs/In0.53Ga0.23Al0.24As/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. Published by AIP Publishing.