1.55 μm InAs/InAlGaAs quantum Dot DFB lasers

For the fabrication of quantum dot (QD) distributed feedback (DFB) lasers, self-assembled InAs/InAlGaAs QDs were grown on the InP/InGaAs grating structures by a molecular beam epitaxy. Ridge-waveguide QD DFB lasers with a stripe width of 3 μm were fabricated. Single-mode lasing operation around the wavelength of 1.56 μm was successfully achieved under the pulsed and continuous-wave (CW) modes at room temperature. The lasing operation was also observed up to 70°C under pulsed mode, which is the first observation on the single-mode lasing around 1.55 μm. The characteristic temperatures calculated from the temperature dependence of the threshold current density were 121.8 K from room temperature to 45°C, which was reduced to 74.2 K from 45°C to 70°C.