Here we will present a reliable (experimentally and numerically proved) technique for multi-spot pattern formation in the focus of a lens (i.e. in the artificial far field). This was done using large square-shaped and/or hexagonal optical vortex (OV) lattices generated by spatial light modulators. Experimental and numerical results showing a controllable far-field beam reshaping when such lattices are generated in the Fourier plane will be discussed. Even more interesting bright structures can be obtained by combining OV lattices (of any type) with different node spacings. We show that the small-scale structure of the observed patterns 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. The orientation of the mixed far-field structures is proven to rotate by 180° when all TCs are inverted.
Optical vortices (OVs) are the only known truly two-dimensional phase dislocations. Because of their spiral phase fronts, the OV interaction results, in the simplest case (when two OVs are presented), in vortex mutual attraction/repulsion or in OV pair rotation. In this work we provide experimental evidences that a stable elementary cell forming the base for a large optical vortex lattice can be created by situating equally and singly charged OVs in the apices of a triangle and square and by nesting an additional control OV with an opposite unit charge in the center of the structure. Experimental data for the rotation of these triangular and quadratic elementary cells vs. OV-to-OV separation as well as the rotation of the same structures vs. propagation distance are presented. Generation and stable propagation of large rigid square-shaped and hexagonal OV lattices is demonstrated.