Parametric light bullets in the absence of group velocity dispersion at the second harmonic frequency

The possibility of the formation of a two-frequency light bullet in a quadratic-nonlinear medium with zero group velocity dispersion coefficient at the second harmonic frequency has been studied analytically. It has been shown that the time duration of the light bullet component at the second harmonic frequency is two times shorter than the pulse duration at the fundamental frequency. At the same time, the transverse dimensions of both components are the same. This light bullet is stable if its aperture exceeds a certain minimum value proportional to the time duration.