Reducing divergence of Vortex beam for Orbital Angular Momentum communication using reflective metasurface

Abstract

The orbital angular momentum (OAM) communication has infinite channel capacity and accuracy. However, current generators for vortex beam have a limitation of large divergence angle. To solve this issue, we propose a meta-lens concept to decrease divergence angle of vortex beam using reflective metasurface. we designed square-shape antennas which cover 360˚ phase to generate vortex beam and simulated the generation vortex beam with a topological charge l=1. The divergence angle of each vortex beam is decreased from 16˚ to 8˚.