The authors report the demonstration of a polarization-controlled vertical-cavity surface-emitting laser (VCSEL), emitting at the telecommunication wavelength. VCSELs are based on an active medium constituted of well elongated InAs quantum dashes (QDHs) nanostructures grown on conventional (001) oriented InP substrate. QDHs present important optical polarization anisotropies according to the [11¯0] crystallographic orientation. Inserted into a VCSEL microcavity, QDH VCSELs show a continuous wave laser operation at 1.6 μm, at room temperature, with a reduced 13 kW/cm2 optical excitation density threshold. The QDH VCSEL output laser polarization is fixed along the same [11¯0] direction. Power and temperature dependant measurements do not show any polarization instabilities and switching on all QDH VCSELs. A polarization extinction ratio as high as 30 dB is deduced from experiments.

InAs quantum dot lasers grown on (311)B InP substrates with AlGaInAs barriers have been fabricated and studied. A large decrease of the threshold current with temperature was observed from 110to140K. In the same temperature range, electroluminescence spectra showed a shape change, an energy shift with temperature, which cannot be fitted with a Varshni law, and a large decrease of the laser linewidth. These results can be related to a delayed thermalisation of carriers within quantum dot ensemble.

InAs quantum dot (QD) formation on InP(001) has been investigated by gas source molecular beam epitaxy as a function of the substrate misorientation, arsenic pressure and temperature. A large improvement on quantum dot shape and density was obtained thanks to the use of substrates misoriented toward the [1 1 10] direction and low arsine flow rate. Round-shaped small QDs (diameter: 26 nm) in high density (9 Â 10 10 QDs/cm 2 ) have been achieved using optimized growth conditions. Room temperature laser emission around 1.55 mm from was obtained with a threshold current density of 1 kA/cm 2 for 1 mm long cavity.