Modification of InGaAs/GaAs heterostructure density of states and optical gain using hybrid quantum well-dots

We show that the density of states and gain spectra of InGaAs/GaAs quantum well-dot (QWD) hybrid nanostructures qualitatively differ from that of quantum wells (QWs) and quantum dots. In QWDs, the density of states does not increase to higher energies and ground-state lasing is maintained up to shorter cavities (higher output loss) as compared to QW lasers emitting in the same optical range. The QWD lasers show lower threshold current densities and better temperature stability than the QW ones. (letter)