40-GHz tunable optical pulse generation from a highly stable external-cavity mode-locked semiconductor laser module

In conclusion, we have demonstrated that a stable EC-MLLD module can generate wavelength tunable optical clock pulses up to 40-GHz by higher-harmonic hybrid mode-locking. Our EC-MLLD which has flexible tunabilities in wavelength, pulse repetition frequency, and pulse width will be very beneficial for the evaluation and the optimization of 40-Gbit/s based optical communication systems.