Programmable manipulation of terahertz beams by hybrid graphene-metal coding metasurfaces

Recently, traditional tunable coding metasurfaces integrated with active components or materials have exhibited not only many functionalities, but also reconfigurable responses, which can execute dynamic beam control. However, these metasurfaces are difficult to realize effective and active terahertz wavefront manipulation due to the inherent defects of the active components or materials, such as high loss, polarization dependence, slow response, and so on, dramatically hindering the potential practical applications of terahertz technologies and devices. To implement programmable manipulation of terahertz beams, here, we propose the reflective-type hybrid graphene-metal coding metasurfaces whose meta-atoms are composed of the different C-shaped metallic split-ring resonators integrated with the graphene, thus, obtaining different coding states by rotating structure and doping graphene. Based on these merits, a couple of coding metasurfaces can effectively achieve various functionalities, including single- and multi-beam deflections, diffusive scattering, and vortex beam, via changed coding patterns. Moreover, these functionalities can further realize dynamic reconfiguration by tuning Fermi energy of graphene. Therefore, the proposed coding metasurfaces would show great potential application prospects in terahertz sensing, display, telecommunication, and imaging.