Vortex Structures in Optical Fibers Under the Influence of Third-Order Dispersion and Self-Steepening Effect

Abstract

The present paper for the first time it is investigated the generation and formation of amplitude-type vortices, propagating in single-mode optical fibers with step-index profile under the influences of third-order dispersion and selfsteepening effect or so called dispersion of nonlinearity of the medium. The main model includes the vector nonlinear amplitude equation, from which a system of two scalar partial differential equations is derived. They describe the evolution of the x and y components of the vector amplitude function  of an optical pulse under the influences of these higher order nonlinear and dispersive phenomena. New exact analytical solutions of the resulting system of equations were obtained in the form of optical vortices. They have amplitude type singularity and they are observed as ring structures in the components of the laser pulses. Numerical simulations of the found solutions are performed. It is shown that the vortex parameter m is related to the number of these ring structures. Significant depolarization of the vector electric field in the spot of the laser radiation is registered.