Theory of passively mode-locked lasers including self phase modulation and group velocity dispersion.

Closed form analytical solutions are obtained for a passively modelocked laser for the case where self phase modulation and group velocity dispersion, in addition to the more conventional mechanisms of saturable absorption and gain, shape the laser pulses. Provided the self phase modulation and group velocity dispersion are related in a manner similar to that which causes soliton formation in optical fibers this additional pulse shaping can reduce the pulse duration below the limit otherwise set by the laser bandwidth.