Harmonic mode-locking order and pulse width control of an amplitude-modulated frequency comb by optical self-injection

Optical self-injection stabilization of a passively mode-locked InGaAs double quantum well semiconductor laser is reported. Time-domain, frequency-domain and spectral domain measurement results in dependence on feedback strength and feedback delay demonstrate pulse width and higher harmonic mode-locking control. Traveling-wave equation simulations allow to explain the measured sequence of harmonic mode-locking orders in dependence on the feedback strength and delay.