Chip-integrated versatile metasurface for simultaneous generation of orthogonal linearly- and circularly-polarized terahertz vortices

Terahertz vortex beams, carrying orbital angular momentum (OAM), are quite desirable to enhance the data transmission capability in telecommunication. However, it faces fundamental and technical challenge in a single metasurface to simultaneously generate orthogonal basis vortices with linear polarization (x- and y-polarity) and circular polarization (left- and right-handed polarity). Here, we proposed a chip-integrated all-dielectric metasurface in terahertz regime, to demonstrate the simultaneous generation of four-channel orthogonal polarized vortex beams at various topological charges. The versatile metasurface was designed only with propagation phase strategy, consisting of polarization-maintaining and polarization-conversion meta-atoms. Simultaneous control of polarization and topological charges in vortex beams was realized by properly arranging birefringent meta-atom arrays to induce additional phases of x- and y-polarization as customized, showing more degrees of freedom for carrying information. The experimental results are in good agreement with the simulations. Such metasurface approach provides complete polarization bases for further synthesis of diverse polarization vortices required for huge-capacity communication.