Flexible generation of OAM mode reconfigurable beams and spinning OAM beams based on active induced magnetism Huygens' metasurface.

Orbital angular momentum (OAM) beams have demonstrated significant potential in the fields of communication, imaging and quantum information science. In particular, active OAM metasurfaces enable flexible and on-demand control of OAM beams without altering their structures, significantly enriching the applications of OAM beams. However, due to the limitations of electrode wiring and unit structure efficiency, most existing active metasurface designs are reflective, hindering the further development of this field. Here, we propose an active induced magnetism Huygens' metasurface to overcome these limitations. We demonstrate that transmissive and high-efficiency OAM mode reconfigurable beams of topological charge l = -1 or l = +1, as well as spatiotemporally modulated spinning OAM harmonic beam of topological charge l = +1 can be generated on-demand. The findings of this study provide a novel approach to achieve more flexible and diversified OAM beamforming, addressing the evolving demands of various OAM-related applications.