Propagation characteristics of astigmatic elliptic vortex beams in nonlocal media with anisotropic nonlinearity

Abstract

The propagation characteristics of the astigmatic elliptic vortex beam (AEVB) in nonlocal media with isotropic and anisotropic nonlinearities are analytically and numerically investigated. Three different kinds of dynamics are discussed: AEVB in nonlinear isotropic media, elliptic vortex beam in nonlinear anisotropic media, and astigmatic circular vortex beam (ACVB) in nonlinear anisotropic media. The isotropic nonlinearity cannot support the formation of elliptic vortex solitons for any input power, and the initial phase-front curvature (IPC) will induce the pulsating behavior of the AEVB. For anisotropic nonlinearity, when the nonlinear anisotropic parameter (NAP) of the medium and the initial ratio of the beam width satisfy γx/γy = (w0y/w0x)2, a quasi-stable elliptic vortex soliton can be obtained, in which the vortex angular velocity and vortex rotation angle evolve periodically. Circular vortex soliton cannot exist in nonlinear anisotropic media, and the rotation of the ACVB can be controlled by adjusting the NAP and the IPC. In both isotropic and anisotropic nonlinear media, the rotation direction of the vortex core is opposite to that of the beam envelope.

Keywords

• Spatial optical soliton
• Strongly nonlocal nonlinearity
• Elliptic vortex beam
• Initial phase-front curvature