Pulse buildup in passively mode-locked monolithic quantum-well semiconductor lasers

The buildup of pulses in a passively mode-locked monolithic semiconductor laser is investigated experimentally and theoretically. A simple model, based on competition between the fundamental and higher order mode-locking ‘‘supermodes,’’ gives a time constant for the buildup in good agreement with the experimental values, which are on the order of 3.5 ns. The theory shows that to minimize the pulse buildup time, the photon life time and the width of the gain spectrum should be minimized, and the gain and the gain modulation, should be maximized.