Digital coding metasurface for Multi-Beam and Multi-Mode OAM in Full-Space

Abstract

A digital coding metasurface is proposed to generate multi-beam and multi-mode orbital angular momentum (OAM) wave in the full space. The 3-bit coding elements are designed for multifunctional integrated digital coding metasurface (MIDCMS) based on the propagation phase theory. The variable-sized phase-shift scheme is applied on metal structures to realize different functionalities in linearly polarized (LP) incidence. Furthermore, the phase distribution of MIDCMS is determined by the pattern convolution theorem. The transmitted and reflected wavefronts are manipulated simultaneously through MIDCMS. As a proof of concept, a metasurface device was fabricated and measured for the four-beam OAM with +1 mode in transmission space and the four-beam OAM with −1 mode in reflection space. Both experimental results and simulated values verify that the proposed MIDCMS can effectively realize the full-space multi-beam multi-mode OAM generation and improve the capacity of information channels, which has potential applications for comprehensive implementations in the future wireless communication systems.

Keywords

• Digital coding metasurface (DCMS)
• Transmission
• Reflection
• Multi-mode
• orbital angular momentum (OAM)