500 GHz optical short pulse generation from a monolithic passively mode-locked distributed Bragg reflector laser diode

Abstract
A 500 GHz optical short pulse train was generated from a passively mode-locked distributed Bragg reflector laser diode (DBR-LD). The repetition frequency was thirteen times the fundamental round trip frequency in the LD, and harmonic mode-locking occurred. The pulse duration was 700 fs and the time-bandwidth product was 0.51, very close to the transform-limited value of a Gaussian waveform, 0.44. To our knowledge, this is the first report on the harmonic mode locking of a monolithic passively mode-locked laser diode.