Vortex solitons in quasi-phase-matched photonic crystals

Abstract

We report solutions for stable compound solitons supported by a three-dimensional (3D) quasi-phase-matched (QPM) photonic crystal in a medium with the quadratic ($\chi ^{(2)}$) nonlinearity. The photonic crystals are introduced with a checkerboard structure, which can be realized by means of the available technology. The solitons are built as four-peak vortex modes of two types, rhombuses and squares. Their stability areas are identified in the system's parametric space, while all bright vortex solitons are subject to strong azimuthal instability in uniform $\chi ^{(2)}$ media. Possibilities for experimental realization of the solitons are outlined too.Comment: 6 pages, 6 figures, 39 reference