Generation of 33 GHz stable pulse trains by subharmonic electrical modulation of a monolithic passively mode-locked semiconductor laser

The first successful demonstration of subharmonic hybrid mode-locking of a monolithic semiconductor laser is reported. 33 GHz pulse trains with reduced phase noise are obtained from the laser by modulating its saturable absorber electrically at cavity subharmonic frequencies of 16.5, 11, and 8.25 GHz. Amplitude modulation as low as -17.4 dBc is observed under 16.5 GHz modulation.