Theory of mode locking of a laser diode with a multiple-quantum-well structure

The multiple-quantum-well structure exhibits both a fast and a slow saturation. The theory of mode locking with such a saturable absorber is investigated, and it is found that the fast component contributes substantially to the formation of short pulses. The presence of the fast-absorber component removes the requirement for gain depletion for the stabilization of the pulse against growth of noise following the pulse for pulses shorter than 1.5 psec. However, the buildup of short pulses from longer ones still calls for gain depletion. The conditions for self-starting and stability against relaxation oscillations to arrive at criteria for the construction of short resonator structures are also investigated.