High-performance 1.3 μm InAs/GaAs quantum-dot lasers with low threshold current and negative characteristic temperature

A high-growth-temperature GaAs spacer layer (HGTSL) is shown to significantly improve the performance of 1.3 mu m multilayer InAs/GaAs quantum-dot (QD) lasers. The HGTSL inhibits threading dislocation formation, resulting in enhanced electrical and optical characteristics and hence improved performance of QD lasers. To further reduce the threshold current density and improve the room-temperature characteristic temperature (T-o), the high-reflection (HR) coating and p-type modulation doping have been incorporated with the HGTSL technique. A very low continuous-wave 2 room-temperature threshold current of 1.5 mA and a threshold current density of 18.8 A cm(-2) are achieved for a three-layer device with a 1 mm HR/HR cavity, while a very low threshold current density of 48 A cm(-2) and a negative T-o are achieved in the p-doped lasers.