Manipulation of Orbital Angular Momentum Energy by Huygens’ Metasurfaces with Donut-shaped Phase Distribution

In wireless communication systems, a multibeam orbital angular momentum (OAM) can be used to increase the number of spatial channels by space-division multiplexing. Furthermore, the multimode OAM is used to enhance the channel capacity by mode-division multiplexing. However, among the previously reported methods, few of them can flexibly and reliably manipulate the energy of OAM in both space-division multiplexing and mode-division multiplexing. In this work, inspired by the theory related to uniform circular antenna arrays, we propose a simple and universal method to manipulate the radiation power and radiation direction of a LP OAM. Firstly, a highly integrated Huygens’ element is designed to achieve high transmission and 360° phase control by modulating mutually interfering electric and magnetic dipole resonances. On this basis, linking the donut-shaped phase distribution of the metasurface and the generated vortex beams was accomplished to manipulate the energy proportion in different modes of the multimode OAM and the energy proportion of energy manipulation between different beams of the multibeam OAM. The proposed power manipulation scheme provides a new way to realize controllable LP OAM, which has potential applications in OAM-based multiplexed communications.