Light bullets in the third harmonic generation mode without matching of phase and group velocities

Abstract The conditions for the formation of a two-color light bullet during the third harmonic generation in a graded-index fiber under conditions of phase and group velocity mismatching are studied. It is shown that the sign of mismatching of the group velocities at the fundamental frequency and at the third harmonic frequency is not significant for the formation of a light bullet. However, the sign of the mismatching between the corresponding refractive indices is quite important. Besides, the phase-group mismatching leads to an expansion of the intervals that are limiting the temporal duration of light bullet, its transverse radius, and the intensities of components at both frequencies. On the other hand, this mismatching reduces the specific contribution of the third-harmonic component to the intensity of light bullet.