Toward 1550-nm GaAs-Based Lasers Using InAs/GaAs Quantum Dot Bilayers

By choice of appropriate growth conditions and optimization of the strain interactions between two closely stacked InAs/GaAs quantum dot (QD) layers, the emission wavelength of the QDs can be significantly extended, giving room-temperature emission from highly uniform QD ensembles in excess of 1500 nm. These QD bilayers are incorporated into edge-emitting laser structures and room-temperature ground-state lasing at 1420 nm and electroluminescence at 1515 nm are observed. Under high-bias conditions, asymmetric broadening of peaks in the laser gain spectra are observed, extending positive net modal gain from the devices to beyond 1500 nm, and the origin of this broadening is discussed.