L. Stoyanov, G. Maleshkov, M. Zhekova, I. Stefanov, D. N. Neshev, G. G.
Paulus, and A. Dreischuh
Abstract.
In this work, we demonstrate
experimentally the formation of 10 different structures consisting of bright beams with
flat phase fronts in the
focus of a lens (i.e., in the artificial
far field). The basic structure
used is a large, stable, square-shaped optical vortex (OV) array composed of vortices with alternating topological charges (TCs). The TCs
of one individual OV, of a subarray of OVs, 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 an offset between the vortices
(off-site alignment). A dramatic reshaping of the beam is
observed in the far field
and shown to be in excellent
agreement with numerical simulations.