Improved performance of 1.3-μm In(Ga)As quantum-dot lasers by modifying the temperature profile of the GaAs spacer layers

We demonstrate greatly improved threshold current and modal gain performance of 1.3-μm quantum-dot (QD) lasers by growing the GaAs spacer layers in two parts, where subtle modification of the spacer layer growth temperature profoundly influences the QDs. Measurements reveal significantly increased ground state (1.3 μm) modal absorption by increasing the growth temperature of the second part of the spacer layer. Improved modal gain is achieved, enabling continuous-wave lasing from a 1-mm-long uncoated laser, even without p-doping. This approach provides a potentially viable route to superior edge-emitting lasers and GaAs-based 1.3-μm vertical-cavity surface-emitting lasers.