The hunt for light bullets and the spontaneous X waves in nonlinear optics

This study presents the search for wave-packets that are both stationary (i.e. invariant during propagation) and localized (i.e. exhibiting a central peak of very small size and duration), in the presence of material dispersion. The new regime that has been investigated, in which the three factors (namely: material chromatic dispersion, X-shape, and nonlinearity) play together their role in affecting the total phase shift, leads to a perfect balance in the ideal case. The process is predicted to occur in quite common operating conditions, namely with focusing Kerr or X⁽²⁾ nonlinearity and normal group velocity dispersion.