Propagation dynamics of abruptly autofocusing circular Airy-Gaussian vortex beams in the fractional Schr\"odinger equation

TL;DR

This paper investigates the propagation and autofocusing behavior of Airy-Gaussian vortex beams in a fractional Schrödinger equation framework, revealing how parameters like Levy index and vorticity influence focusing properties.

Contribution

It introduces a new model of Airy-Gaussian vortex beams in fractional Schrödinger systems and analyzes their unique autofocusing dynamics through numerical simulations.

Findings

Autofocusing occurs abruptly and is followed by a rebound.

Focusing properties depend on Levy index, beam width, and vorticity.

Maximum peak intensity occurs near Levy index 1.4.

Abstract

We introduce axisymmetric Airy-Gaussian vortex beams in a model of an optical system based on the (2+1)-dimensional fractional Schr\"odinger equation, characterized by its L\'evy index (LI). By means of numerical methods, we explore propagation dynamics of the beams with vorticities from 0 to 4. The propagation leads to abrupt autofocusing, followed by its reversal (rebound from the center). It is shown that LI, the relative width of the Airy and Gaussian factors, and the vorticity determine properties of the autofocusing dynamics, including the focusing distance, radius of the focal light spot, and peak intensity at the focus. A maximum of the peak intensity is attained at intermediate values of LI, close to LI=1.4 . Dynamics of the abrupt autofocusing of Airy-Gaussian beams carrying vortex pairs (split double vortices) is considered too.