Radiation characteristics of injection lasers based on vertically coupled quantum dots (original) (raw)

We have studied injection lasers based on InGaAs/GaAs vertically coupled quantum dots (QD) grown by molecular beam epitaxy. The threshold current density decreases by one order of magnitude down to 90 A cm −2 (300 K) with an increase of the number of QD stacks (N ) up to 10. For N ≥ 3 lasing occurs via the QD ground state up to room temperature. Differential efficiency increases with N up to 50%. No change in range of high temperature stability of threshold current density (J th ) was observed, while the characteristic temperature (T 0 ) measured at 300 K increases from 60 to 120 K. Using InGaAs-AlGaAs QD with higher localization energy allowed us to decrease J th down to 60 A cm −2 and to increase the differential efficiency up to 70%.