Generation of multi-ring perfect vortex beams with tunable intensity distribution

Perfect optical vortices (POVs), consists of a single bright ring structure, has been widely studied owing to its radius independent of orbital angular momentum (OAM). However, most of the existing works about POVs are limited to single ring structure. Flexible shaping of intensity distribution of POVs is vital for multiple applications. In this paper, we propose a method generate phase tunable multi-ring perfect optical vortices (MR-POVs) where each ring size is independent of its OAM. The scheme is based on the radical discontinuous spiral phase plate (RD-SPP) which introduces controllable phase jumps along radial direction. It is experimentally demonstrated that the vortex nature of the MR-POVs through an interferometric method, showing that each ring of MR-POVs possesses same topological charge value (magnitude and sign), and the intensity ratio between each ring can be freely regulated by adjusting phase distribution, which could offer more flexible optical gradient force for guiding and transporting particles. In addition, simulation and experimental results show that the integer and fractional MR-POV can generated by the independent regulation of angular and radial factors. This work expands our understanding of multi-ring POV and may provide a new idea for optical tweezers and OAM communications.