Fig. 1. Schematic structure of the QD samples (Inset: TEM image of the QD active region)

Fig. 2. Schematic diagram of QD laser structure

Fig. 3. Simulated reflectivity spectra with different central wavelengths

Fig. 4. PL spectra measured at room temperature for the undoped and p-doped QD materials

Fig. 5. Energy band diagrams of the undoped and p-doped QD samples (the dashed lines are the potential profiles after annealing). (a) Undoped; (b) p-doped

Fig. 6. Cavity length dependence of the threshold current density of ground state for undoped and p-doped QD lasers (Inset: lasing spectra of undoped and p-doped QD lasers)

Fig. 7. Measured reflectivity spectra and EL of QD laser. (a) Reflectivity spectra with λ=1480 nm and EL of p-doped QD laser; (b) lasing spectra of 300 μm p-doped QD laser with coated