Multiplexed Generation of Generalized Vortex Beams with On-Demand Intensity Profiles Based on Metasurfaces

Optical vortex beams (VB) have provided a new degree of freedom for carrying optical information due to the unbounded number of orthogonal orbital angular momentum (OAM) channels. Due to the presence of phase singularity, VBs possess a dark zone in the center surrounded by a bright ring whose radius is directly related to the OAM carried by the beam. Here multiplexed generalized vortex beams (GVB) are demonstrated with various custom-defined closed-loop beam profiles, including polygons, star and windmill, by tailoring the local phase gradient along the azimuthal direction. By utilizing different polarization channels of metasurfaces, multiple GVBs with independent intensity profiles are generated. This approach provides a playground for realizing various optical modulating capabilities, such as precise particle manipulation, optical source, and OAM encryption.