A circular Airy vortex beam carrying two point vortices symmetrically on the x-axis with the same and opposite signs

TL;DR

This paper investigates how the position of two point vortices in circular Airy vortex beams influences their focusing behavior, revealing tunable patterns that could benefit applications in micromanipulation and communication.

Contribution

It introduces a detailed analysis of vortex loading positions in CAVBs and their impact on focusing, supported by both simulations and experiments.

Findings

Vortex loading position significantly affects auto-focusing behavior.

Merged vortices can be separated or form Bessel patterns by adjusting dv.

Experimental results confirm simulation predictions.

Abstract

We study circular Airy vortex beams (CAVBs) with two same or opposite point vortices symmetrically loaded on x-axis, inside, onside and outside of the main ring (The absolute value of topological charge is one). It is found that the loading position (denoted as dv) can significantly tune the auto-focusing behaviour. For two vortices with same signs, when dv is near zero, the double vortices approximately merge at the focal plane. But as dv increases, the merged vortices will gradually separate along the y-axis. When dv is large, the focal spot becomes Bessel-shaped pattern. For opposite vortices, when dv is small, the focusing pattern is Bessel-shaped (no vortex exists in the centre) but not strictly in the centre. With the increase of dv, the original spot gradually moves up along the y-axis and transfers its energy to the newborn spot below x-axis, at the same time, the newborn spot moves towards the centre. When dv is large, the focus returns to a Bessel-like pattern. Good agreements have been achieved between simulations and experiments. The tailoring effect of dv of the two vortices on the focal pattern may have potential applications in micromanipulation, communication and other fields.