Spatial beam reshaping and spectral broadening in quadratic crystals

Nonlinear optics in crystals with quadratic susceptibility has been largely explored along the last decades, with a particular emphasis on spatial solitons. When in the initial part of the propagation, the nonlinear length is much shorter than the diffraction length, rather than solitons, in these crystals it is possible to observe strong beam reshaping and spectral broadening. This mechanism of nonlinear beam evolution can be induced by combining high laser energies and large input diameters, so to reduce the contribution of diffraction in the initial steps of the propagation.