Vortex solitons in quasi-phase-matched photonic crystals

TL;DR

This paper demonstrates the existence and stability of vortex solitons in a three-dimensional quasi-phase-matched photonic crystal with quadratic nonlinearity, highlighting their potential for experimental realization.

Contribution

It introduces stable four-peak vortex solitons in a 3D photonic crystal with checkerboard structure, expanding understanding of soliton stability in quadratic nonlinear media.

Findings

Stable vortex solitons identified in the system's parameter space

Rhombus-shaped solitons have broader stability domains

All bright vortex solitons are azimuthally unstable in uniform media

Abstract

We report solutions for stable compound solitons in a three-dimensional quasi-phase-matched photonic crystal with the quadratic ($\chi ^{(2)}$) nonlinearity. The photonic crystal is 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 (intersite- and onsite-centered self-trapped states, respectively). Their stability areas are identified in the system's parametric space (rhombuses occupy an essentially broader stability domain), 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.