Pulse properties of external-cavity mode-locked semiconductor lasers

The performance of an external-cavity mode-locked semi-conductor laser is investigated both theoretically and experimentally. The optimization analysis focuses on the regimes of stable mode locking and the generation of sub-picosecond optical pulses. We demonstrate stable output pulses down to one picosecond duration with more than 30 dB trailing pulse suppression. The limiting factors to the device performance are investigated on the basis of a fully-distributed time-domain model. We find that ultrafast gain dynamics effectively reduce the pulse-shaping strength and inhibit the generation of femtosecond optical pulses.