Polarization anisotropy of electroluminescence and net-modal gain in highly stacked InAs/GaAs quantum-dot laser devices

Abstract

We studied polarization anisotropy of the electroluminescence (EL) and net-modal gain in 40-stacked InAs/GaAs quantum dot (QD) laser device structures. Since the electronic coupling between the QDs enhanced the transverse-magnetic (TM) polarization component, the [110] waveguide devices exhibited a laser oscillation from the ground state in not only transverse-electric (TE) component but also TM component. The polarized EL intensity was almost isotropic at low injection current density while it exhibited dramatically large anisotropy after laser oscillation, which was attributed to a lower threshold current density in the TE component. In contrast, the [110] waveguide device exhibited no laser oscillation neither in the TE component nor in the TM component and polarization insensitive EL characteristic.