Radial phase modulated spiral zone plate for generation and manipulation of optical perfect vortex

Abstract

We propose a novel diffractive element to produce a perfect vortex beam. Flexibility in creating any perfect vortex beam is one of the considerable advantages of this method. Moreover, simplicity in creating the element is another interesting feature of this technique. We simply produce the proposed element by shifting the phase of a spiral zone plate and demonstrate how the phase shift enables us to manage the size of the generated perfect vortex. Further studies illustrate that the shape of the vortex is preserved in a long focal depth, while the phase map rotates around the propagation axis. In addition, all experimental results denote congruence with the respective results from simulation.