Self-Start Mode-Locking by Multi-Spatial-Mode Active Waveguiding

We demonstrate a principle of self-start mode-locking in a compact semiconductor laser diode, where the needed saturable absorption action is provided by spatial effects resulted from multi-mode active waveguding. The demonstrated device operates at 1.54 um wavelength range and has a repetition rate of 47 GHz. The pulse width is below 5 ps and the average power coupled to cleaved single-mode fiber is about 0 dBm.