Far-field beam reshaping by manipulating the topological charges of hexagonal optical vortex lattices

In this work, we demonstrate experimentally the formation of eight different basic structures consisting of bright beams with flat phase fronts in the focus of a lens (i.e. in the artificial far-field). In all cases considered, the used input structure is a large, stable, hexagon-shaped optical vortex (OV) array composed of vortices with alternating topological charges (TCs). The TCs of one individual OV or of the complete OV lattice were erased/doubled in the cases of perfect superposition (on-site alignment) or are manipulated in phase in the cases of different offsets between the lattice elementary cells (off-site alignments). A dramatic reshaping of the input beam is observed in the far-field and it is shown to be in excellent agreement with the numerical simulations.