Abstract
In the present work we show experimentally and by numerical calculations a substantial far-field beam reshaping by mixing square-shaped and hexagonal optical vortex (OV) lattices composed of vortices with alternatively changing topological charges. We show that the small-scale structure of the observed pattern results from the OV lattice with the larger array node spacing, whereas the large-scale structure stems from the OV lattice with the smaller array node spacing. In addition, we demonstrate that it is possible to host an OV, a one-dimensional, or a quasi-two-dimensional singular beam in each of the bright beams of the generated focal patterns. The detailed experimental data at different square-to-hexagonal vortex array node spacings shows that this quantity could be used as a control parameter for generating the desired focused structure. The experimental data are in excellent agreement with the numerical simulations.
Highlights
Due to the spiral phase profiles of their wavefronts, optical vortices (OVs) are the only known truly two-dimensional (2-D) singular beams[1]
In frame (a) the OVs constituting one elementary cell of the hexagonal lattice are encircled. In this way we show the large ratio between the node spacings of both lattices and the broadening of each OV of the square lattice propagating from SLM1 to SLM2 as compared to the width of the newly-born OVs from the hexagonal lattice just after SLM2
In this work we show significant far-field beam reshaping by mixing square-shaped and hexagonal optical vortex lattices
Summary
Due to the spiral phase profiles of their wavefronts, optical vortices (OVs) are the only known truly two-dimensional (2-D) singular beams[1]. Nesting two OVs of opposite TCs at the same positions result in their translation with respect to the host beam, in their mutual attraction and, eventually, in annihilation. In both self-focusing and self-defocusing third-order nonlinear media, the described interactions remain qualitatively the same during the initial stage of nonlinear evolution[8]. TC of an isolated OV or even of a large OV array[24,25,26] is an essential part of the physics of the present results We demonstrate that this is valid for a single OV, and holds for OV lattices (square-shaped and hexagonal) composed of hundreds of OVs on a single background beam. The numerical data are shown to be in excellent agreement with the experimental results
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