experimentally investigated in a∼ 40 GHz quantum-dash mode-locked laser diode subject
to optical injection of 10 GHz pulses. In comparison to the 75 kHz linewidth exhibited by the
beat-tones in passive mode-locking conditions, a remarkable reduction to less than 8 Hz is
achieved when the laser is under optical injection. From this beat-tone signal, an integrated
root-mean-square timing jitter of 64 fs is calculated. In addition, a quadratic profile of the …