Long-wavelength quantum dot lasers on GaAs substrates

We study 1.3 micrometer diode lasers based on self-organized InAs quantum dots grown by MBE on GaAs substrates. Overgrowing the InAs quantum dot array with thin InGaAs layer allows us to achieve 1.3 micrometers emission and keep sufficiently high surface density of quantum dots. Using transmission electron microscopy we show that the main reason for the long wavelength PL shift InAs/InGaAs quantum dots is non-uniform distribution of In in InGaAs leading to the increase in effective volume of a quantum dot. Long stripe lasers showed low threshold current density (<100 A/cm2), high differential efficiency (>5O%). and low internal loss (^l-2cm(-1)). Maximum output power for wide stripe lasers was as high as 2.7 W and for single-mode devices 110 mW. The lasing wavelength for VCSELs was I .28 micrometrs. The threshold current for the device with the 12 micrometer apperture was 1.8 mA. The output power of 220 mW at drive current of 2.4 mA was observed under pulsed mode.