Double-Ring Vortex Beams Generated by Coaxial Superposition of Laguerre-Gaussian Modes

摘要

We propose the generation of double-ring vortex beams by coaxial superposition of Laguerre-Gaussian modes with different topological charge numbers and different waist parameters. The formation and distribution characteristics of double-ring vortex beams are analyzed in theory. A computer-generated holography based on conjugate-symmetric extension is applied to encode the holograms, with which we reconstruct the double-ring vortex beams by optical experiments. It is found that each ring of the double-ring vortex beams carries different orbital angular momentum. Furthermore, when the internal topological charge remains unchanged, the distance between the two rings becomes bigger with the increase of external topological charge. Excellent agreements between theoretical and experimental results are observed. The double-ring vortex beams may find their potential application value in the fields of micro particles manipulation and optical information encoding as different orbital angular momentum is respectively carried by the internal and external rings.