Spatial dispersion control for self-focusing suppression by Laue-type photonic crystals

We propose and experimentally demonstrate an integrated approach to suppress Kerr self-focusing by engineering the spatial dispersion of a medium using Laue-type photonic crystals. The photonic crystal, featuring longitudinally chirped and constant-period sections, was designed using a beam-propagation model and fabricated in a UV-fused-silica substrate by femtosecond direct laser writing with a Bessel beam. We characterized the structure by performing nonlinear transmission measurements and analyzing the evolution of the output beam profile as a function of the input pulse energy. Compared to a non-resonant reference structure and the bulk material, the dispersion-engineered photonic crystal successfully counteracts self-focusing, resulting in a 12% increase in the nonlinear absorption threshold. This work presents the first practical demonstration of nonlinearity management through spatial dispersion control in a monolithic photonic crystal, offering a new pathway to bypass the power-scaling limitations of nonlinear processes in solid-state materials.