Broadband polarization-independent OAM-multiplexed beam manipulation based on Huygens' metasurface

Orbital angular momentum (OAM) vortex waves have become a prominent topic in scientific research and engineering applications. With the developments of metasurface-based OAM generation and manipulation technologies, Huygens' metasurfaces demonstrate the advantages of low profile and simple structure. In this paper, we propose a broadband Huygens' metasurface capable of polarization-independent OAM-multiplexed beam deflections. Firstly, a highly efficient polarization-independent Huygens' meta-atom is designed, and then the dual-polarized 3-bit phase profiles are constructed to generate the polarization-independent OAM-multiplexed beams. On this basis, dual-polarized phase sequences are incorporated into the 3-bit phase profiles, enabling the broadband polarization-independent OAM-multiplexed dual beam deflections in two orthogonal planes. We fabricated and measured three metasurface samples, and the experimental results are consistent with the simulations, confirming the feasibility and practicality of the proposed method. The proposed metasurface operated at 8.5 GHz-11.5 GHz, achieving a 30% relative bandwidth and 14.8% aperture efficiency. We believe this design demonstrates promising potential for applications in multi-target wireless communications and wide-range radar detections.