Self mode-locking and passive mode-locking in monolithic two-section InGaAsP/InP quantum well laser diode

We analyze different mode-locking regimes of a monolithic two-section InGaAsP/InP quantum well mode-locked laser. By varying the electrical operation conditions, we investigate and compare the transition from self mode-locking via four wave mixing to passive mode-locking. The results indicate that self mode-locking predominates, resulting in pulse durations as short as 330 fs, accompanied by a narrow linewidth frequency comb. In contrast, passive mode-locking does not provide sub-ps pulses and delivers significantly broadened comb lines.