Influence of phase self-modulation on the temporal characteristics of ultrashort pulses emitted by solid-state lasers

The kinetics of changes in the temporal profile and frequency modulation of pulses under conditions of phase self-modulation and allowing for the width of the gain profile was analyzed using a model which postulates that the fluctuation pattern of the radiation emitted by a passively mode-locked solid-state laser has the form of an intensity peak against a background which is constant over the resonator period. The rms duration and the half-height duration of the largest peak were compared and the fraction of the pulse energy in the largest peak was studied to analyze the degree of deformation of the pulse temporal profile. It was found that, for moderate values of the phase self-modulation parameters, ultrashort pulses with a small fraction of energy in the side satellites and almost linear chirp in the central peak can be generated by tuning the system to the second threshold in a train of giant pulses. For large phase self-modulation parameters, this can be achieved by using a spectrum-limiting filter in the resonator.