Origin of the temporal structure of ultrashort laser pulses

An analysis was made of the mechanism of formation of a substructure in ultrashort pulses emitted by a mode-locked neodymium laser. The substructure was due to a nonlinear correction to the refractive index of the active medium subjected to the high-power optical field of a pulse. A numerical calculation relating to this process was made and the results obtained were compared with the experimental data.