Continuous-wave low-threshold performance of 1.3-μm InGaAs-GaAs quantum-dot lasers

The understanding of material quality and luminescence characteristics of InGaAs-GaAs quantum dots (QD's) is advancing rapidly. Intense work in this area has been stimulated by the recent demonstration of lasing from a QD active region at the technologically important 1.3-mu m wavelength from a GaAs-based heterostructure laser. Already, several groups have achieved low-threshold currents and current densities at room temperature from In(Ga)As QD active regions that emit at or close to 1.3 mu m, In this paper, we discuss crystal growth, QD emission efficiency, and low-threshold lasing characteristics for 1.3-mu m InGaGs-GaAs QD active regions grown using submonolayer depositions of In, Ga, and As. Oxide-confinement is effective in obtaining a low-threshold current of 1.2 mA and threshold-current density of 19 A/cm(2) under continuous-wave (CW) room temperature (RT) operation. At 4 K, a remarkably low threshold-current density of 6 A/cm(2) is obtained.