InAs/InGaAs quantum dot laser with high ground-state modal gain grown by solid-source molecular-beam epitaxy

InAs self-organized quantum dots covered with In_0.33Ga_0.67As layer have been grown on GaAs substrates by solid-source molecular beam epitaxy. The effect of the InGaAs thickness has been discussed. As-cleaved 2.54-mm-long laser diode using triple stacks of InAs QDs covered with 6.0 ML In_0.33Ga_0.67As layer demonstrates a lasing wavelength of 1,214 nm and a threshold current density of 124 A/cm². The ground-state saturation gain of 23 cm^-1 is achieved due to an energy spacing of 85 meV between the ground and the first excited quantum dot levels and the high dot density.