title: Tunable graphene metasurfaces by discontinuous Pancharatnam-Berry phase shift.
abstract: Metal-dielectric-graphene three-layer structures are proposed to improve the interaction of graphene micro- and nanostructures with incident waves, as the upper graphene cut-wire layer introduces a discontinuous Pancharatnam-Berry phase profile. A semi-analytical method based on the Jones calculus is conducted to investigate the conversion efficiency of cross-polarized light on this graphene metasurface for circularly polarized wave incidence, which predicts that the physical constraint (25%) of cross-coupling conversion efficiency for individual graphene layers can be overcome. Numerical simulations confirm the conclusion and demonstrate an efficiency as high as 60%. Based on this mechanism, high-efficiency anomalous reflection surfaces and flat focal mirrors are designed with the tunability of reflection angles and one order of magnitude improved focusing intensity. This method paves the way to engineering high-efficiency graphene metasurfaces for tunable electromagnetic wave manipulation.
authors.affiliation: Key Lab of Nanodevices and Applications-CAS & Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123, People's Republic of China. University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Hu
authors.forename: Long
authors.initials: L
authors.lastname: Wen
authors.forename: Shichao
authors.initials: S
authors.lastname: Song
authors.forename: Qin
authors.initials: Q
authors.lastname: Chen