InGaAs–GaAs Quantum-Dot Mode-Locked Laser Diodes: Optimization of the Laser Geometry for Subpicosecond Pulse Generation

The effect of cavity geometry on both pulsewidth and pulse output power is systematically investigated for a monolithic mode-locked quantum-dot laser diode. Subpicosecond pulse generation is demonstrated, and trends in pulsewidth and pulse output power are correlated to the ratio of the gain-to-absorber section lengths. A three-fold reduction in the pulsewidth, from 2.3 ps to 800 fs, is observed for a change in the gain-to-absorber section length ratio of 14 : 1 to 3 : 1. In addition, an associated five-fold increase in average power and 14-fold increase in peak power are also observed.