Fig. 1. Schematic illustration of the laser epitaxial structure; the close-up on the right depicts one period of the active region.

Fig. 2. Optical spectrum at 18 mA (3×Ith, red marker) of the QD laser. The inset shows the light-current characteristics measured at room temperature (20°C).

Fig. 3. Measured optical spectra for the QD laser. In black, the free-running laser without optical injection. In blue, the laser is injection-locked. When the wavelength detuning is increased by 11 pm, the blue lines are shifted towards the red lines.

Fig. 4. Spectral dependence of the αH factor measured by ASE (blue) and ASE-IL methods (red) for the epitaxial QD laser. The inset shows the αH-factor values for the QW laser. The vertical dotted line indicates the αH-factor value at FP gain peak.

Fig. 5. Measured damping factor (γ) as a function of the squared relaxation oscillation frequency (fRO2), both for QD and QW lasers.

Fig. 6. Squared relaxation oscillation frequency (fRO2) versus the output power, both for QD and QW lasers.

Fig. 7. The simulated αH factor as a function of the output power for the (a) QW laser and (b) QD laser. Superimposed black stars in (b) correspond to experimental data from Ref. [15].

Fig. 8. Schematic of the optical feedback apparatus used both for static and dynamic characterizations.

Fig. 9. Optical spectra under free-running (blue) and 100% (red) of total reflection for QD laser at (a) 3×Ith and (b) 4×Ith.

Fig. 10. (a) BER curves for solitary QD laser and with 100% of backreflection in B2B configuration and after transmission. Eye diagrams (b) of the solitary laser and (c) with 100% feedback in B2B configuration. Eye diagrams (d) of the solitary laser and (e) with 100% feedback after transmission.