Birth and evolution of an optical vortex

TL;DR

This paper investigates the formation and evolution of optical vortices created by imprinting phase singularities on Gaussian beams, combining experimental observations with the circular-beam theory to understand their propagation and structure.

Contribution

It experimentally validates the circular-beam theory for optical vortex evolution and analyzes differences in vortex structure during propagation and imaging.

Findings

Experimental confirmation of circular-beam theory predictions

Identification of differences in vortex structure between propagation and imaging

Insights into the radial growth dynamics of optical vortices

Abstract

When a phase singularity is suddenly imprinted on the axis of an ordinary Gaussian beam, an optical vortex appears and starts to grow radially, by effect of diffraction. This radial growth and the subsequent evolution of the optical vortex under focusing or imaging can be well described in general within the recently introduced theory of circular beams, which generalize the hypergeometric-Gaussian beams and which obey novel kinds of ABCD rules. Here, we investigate experimentally these vortex propagation phenomena and test the validity of circular-beam theory. Moreover, we analyze the difference in radial structure between the newly generated optical vortex and the vortex obtained in the image plane, where perfect imaging would lead to complete closure of the vortex core.