Effect of Scale Characteristics of a Femtosecond Mid-IR Wave Packet on the Threshold Power of Filamentation

The dependence of the formation process of a light bullet on the relation between diffraction and dispersion lengths of the femtosecond mid-IR wave packet during its propagation in transparent dielectrics is studied. It is found that the ratio of the diffraction length of the wave packet to its dispersion length is the similarity parameter for the light bullet formation under conditions of anomalous dispersion of the group velocity. The value of the filamentation threshold power taken relative to the critical power of stationary self-focusing is also defined by the introduced similarity parameter and increases with it.