Terahertz vortex beam and focusing manipulation utilizing a notched concave metasurface

In order to effectively improve the information carrying capacity of modern wireless communication systems, vortex beams with orbital angular momentum (OAM) have attracted extensive attention due to extending communication capacity through orthogonal channels with different OAM modes carrying different information. However, the reported studies are only concentrated on single-function vortex beam. Here, we propose a notched concave metasurface to generate for multifunctional vortex beams such as four vortex beams, focusing vortex beams, deviation focusing vortex beams, and multi-beam vortex beam under different polarization. The theoretical results show good agreements with the full-wave simulations. The designed metasurface enables diversified promising applications for flexible manipulation OAM and terahertz wave polarization detection in future terahertz wireless communication.