Polarized photoluminescence spectroscopy of single self-assembled InAs quantum dots

We have investigated the spin relaxation of carriers in single InAs/GaAs self-assembled quantum dots using near-field optical spectroscopy. Polarized photoluminescence spectroscopy of Zeeman split peaks in an external magnetic field allows us to investigate spin relaxation in the excited states. The excitation energy dependence of the polarization of each spin component shows the suppression of spin relaxation to be quenched at higher relaxation energies. This effect suggests a change in relaxation processes in the self-assembled dot systems.