Artificial Perfect Electric Conductor-Perfect Magnetic Conductor Anisotropic Metasurface for Generating Orbital Angular Momentum of Microwave with Nearly Perfect Conversion Efficiency

TL;DR

This paper introduces two novel PEC-PMC anisotropic metasurfaces capable of nearly perfect conversion of plane waves into vortex beams carrying orbital angular momentum, enhancing efficiency and flexibility in electromagnetic applications.

Contribution

The work presents two innovative metasurface designs that achieve nearly perfect OAM conversion efficiency, surpassing previous metasurface capabilities with improved phase control and topological charge flexibility.

Findings

Achieved nearly perfect OAM conversion efficiency.

Continuous metasurface provides smooth phase patterns.

Discrete scatterer metasurface allows arbitrary topological charges.

Abstract

Orbital angular momentum (OAM) is a promising degree of freedom for fundamental studies in electromagnetics and quantum mechanics. The unlimited state space of OAM shows a great potential to enhance channel capacities of classical and quantum communications. By exploring the Pancharatnam-Berry phase concept and engineering anisotropic scatterers in a metasurface with spatially varying orientations, a plane wave with zero OAM can be converted to a vortex beam carrying nonzero OAM. In this paper, we proposed two types of novel PEC (perfect electric conductor)-PMC (perfect magnetic conductor) anisotropic metasurfaces. One is composed of azimuthally continuous loops and the other is constructed by azimuthally discontinuous dipole scatterers. Both types of metasurfaces are mounted on a mushroom-type high impedance surface. Compared to previous metasurface designs for generating OAM, the proposed ones achieve nearly perfect conversion efficiency. In view of the eliminated vertical component of electric field, the continuous metasurface shows very smooth phase pattern at the near-field region, which cannot be achieved by convectional metasurfaces composed of discrete scatterers. On the other hand, the metasurface with discrete dipole scatterers shows a great flexibility to generate OAM with arbitrary topological charges. Our work is fundamentally and practically important to high-performance OAM generation.