Modulation instability and interaction of non-paraxial beams in self-focusing Kerr media

The modulation instability of broad light beams is investigated in self-focusing Kerr media beyond the paraxial approximation. The theory is based on a non-paraxial equation including the contributions depending on the longitudinal component of the electric field. Theoretical analysis shows that spatial solitons can exist and the soliton width decreases monotonously with the intensity. The coherent interactions of multiple non-paraxial solitons are also discussed in this kind of media.