Charge identification of composite vortex beams through self-referenced interferometry

Abstract

Composite vortex (CoV) beams are the structured beams represented through the superposition of multiple Laguerre-Gaussian modes. Composite vortices have recently gained importance owing to their unique properties originating from the multiple-phase singularities, and therefore, techniques for their generation and characterization play a vital role. The present study reports a method for identifying the topological charges of singular points embedded in CoV beams using self-referenced interferometry under the effect of atmospheric turbulence. The beam carrying composite vortices interferes with its own conjugate copy, resulting in a well-defined interference pattern, which, on analysis, reveals the sign and magnitude of topological charge. Simulation and experimental results have been presented that verify the effectiveness of the proposed technique. The results show that the proposed method can effectively identify the multiple-phase singularities through interferometry without the use of any additional reference beam.