InAs/GaAs quantum-dot laser diode lasing at 1.3 μm with triple-stacked-layer dots-in-a-well structure grown by atomic layer epitaxy

We report the first demonstration of room-temperature (RT) lasing at 1.3 μm from the ground state of three-stacked InAs quantum dots (QDs) in an In_0.85Ga_0.85As quantum well, which was grown by atomic layer epitaxy (ALE). For an as-cleaved device with a 2000-um-long × 15-μm-wide ridge structure, the threshold current density (J_th) at RT is 1.55 A/cm² with the ground state lasing at 1310 nm under pulsed operation. The thermal coefficient of a lasing wavelength shift is 0.53 nm/K and the characteristic temperature is 103 K near RT. The lasing wavelength of the QD laser diodes (LDs) shows simultaneous lasing and the state switching from the ground state at 1310nm and to the first excited state at 1232nm with increasing injection current owing to the gain saturation of the ground state. The performance of ALE QD-LD is comparable to that of the conventional Stranski-Krastanov QD-LD.