Full-space energy-controlled multi-wavefront generators enabled by hybrid graphene-VO2 terahertz metasurfaces

In terahertz communication, multi-wavefront reconfigurable metasurfaces allowing for energy control are highly desirable for multiple channels and high capacity. However, existing metasurfaces can only produce limited wavefronts in either transmission or reflection space, severely hindering their practical application ranges. Herein, a dual-controlled reconfigurable metasurface integrated with graphene and VO2 is demonstrated for an energy-controlled multi-wavefront generator in full-space. By altering the geometry sizes and rotation angles of the meta-atoms as well as external excitations, the polarization independent phase responses are achieved to actively generate energy-controlled multiple wavefronts in full-space. As a proof-of-concept demonstration, three types of full-space metasurfaces are constructed to respectively realize various meta-deflectors, metalens/meta-deflector/orbital angular momentum (OAM) generator, and multimode OAM generator in full-space by utilizing the spin-decoupling method. Moreover, the intensities of these wavefronts can be actively modulated by adjusting the Fermi energy of graphene. Therefore, such diversified metasurface will possess a promising application prospect in terahertz multifunctional devices, and communication and imaging systems.