Versatile broadband generation of polygonal perfect vortex beams in the visible spectrum

Optical vortex (OV) beams characterized by their twisted wave phase and the orbital angular momentum (OAM) have garnered significant interest and found practical utility in diverse applications like optical communication, particle manipulation, and many more. The topological charge plays a crucial role in defining and recognizing the OV beams, which are controlled by the number of twisted waves and the radius of the intensity profile. The reliance of OV beams on the topological charge poses limitations in numerous applications that necessitate coupling and higher topological charge values. The perfect vortex beams integrated with the Metasurface are the nanoscale solution for the abovementioned issues. Previous studies have controlled the shape and size of the ideal vortex beam. This study demonstrates the broadband generation of polygonal perfect vortex beams through all-glass metasurfaces, aiming to manipulate the beam's shape while preserving its orbital angular momentum (OAM) and radius. The presented metasurfaces carry an array of nanoantennas made of zinc sulfide material to generate a broadband perfect vortex beam within the visible spectrum, from 475 nm to 650 nm. For proof of concept, we have generated OV beams exhibiting multiple shapes like hexagons and octagons, and these shapes helped us make asymmetric intensity profiles. These irregular intensity distributions will help to create flexible optical traps for nanoparticles. The implications of our study include nano-optical trapping, optical manipulation, and optical communication.