Low-threshold operation of 1.3-mu m GaAsSb quantum-well lasers directly grown on GaAs substrates

GaAsSb quantum-well (QW) edge-emitting lasers grown on GaAs substrates were demonstrated. The optical quality of the QW was improved by optimizing the growth conditions and introducing multi-QW to increase gain. As a result, 1.27-mu m lasing of a GaAs0.66Sb0.34-GaAs double-QW laser was obtained with a Low-threshold current density of 440 A/cm(2), which is comparable to tha t in conventional InP-based long-wavelength lasers, 1.30 mu m lasing with a threshold current density of 770 A/cm(2) was also obtained by increasing t he antimony content to 0.36, GaAsSb QW was found to be a suitable material for use in the active layer of 1.3-mu m vertical-cavity surface-emitting la sers.