A 1.33 µm InAs/GaAs quantum dot laser with a 46 cm⁻¹modal gain

We report on 1.33 µm quantum dot (QD) lasers grown on GaAs substrates that show a modal gain of 45 cm −1 , low threshold current density of 150 A cm −2 and room-temperature continuous wave output power of 2.5 W. The active region is based on ten InAs/InGaAs/GaAs quantum dot layers formed by activated phase separation. High structural quality of the active region is achieved, owing to minimization of the total amount of strained material per QD layer. The optical confinement factor is increased by exploiting high Al composition (80%) in the cladding layers. A modal gain over 20 cm −1 in the 1315–1345 nm wavelength range is revealed by the Hakki–Paoli technique at a low current density of 500 A cm −2 .