Generation of dual-polarization orbital angular momentum vortex beams with reflection-type metasurface

Orbital angular momentum (OAM) vortex beams can provide a new degree of freedom for information modulation at a physical level, which has great prospects to expand channel capacity in the fields of wireless microwave and optical communication. In this paper, a reflection-type anisotropic metasurface is proposed to transform the incident plane wave into reflected vortex beams by modulating the phase of wavefront. Single vortex beam, multi-beam vortex beams with different mode beams are demonstrated. Under the incidence of orthogonal linearly polarized waves, independent vortex beams can be generated at 15 GHz for polarization multiplexing. Besides, the OAM spectrum decomposition is performed to analyze the purity of the OAM modes based on a Fourier transformation. The results presented in the paper demonstrate the feasibility of generating vortex beams on metasurface within a subwavelength thickness, which may promote the development of electromagnetic/optical integration devices with polarization multiplexing techniques.