Theory of active mode locking of a semiconductor laser in an external cavity

An analytical treatment is given for the active mode locking of a semiconductor laser in an external resonator. The width of the mode-locked pulses is obtained as a function of the laser and cavity parameters and the amount of frequency detuning. The effects of self-modulation and saturation are included in the treatment. The pulse output is compared with that obtained by a strong modulation of the laser diode with no external cavity.