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Abstract: Although recent progress in metasurfaces has shown great promise for applications, optical properties in metasurfaces are typically fixed by their structural geometry and dimensions. Here, an electrically controllable amplitude of anomalously‐refracted waves in a hybrid graphene/metasurface system are experimentally demonstrated, which consists of an artificially constructed two‐dimensional metallic apertures array and naturally occurring two‐dimensional carbon atoms (graphene) in the subwavelength‐scale (< λ/10). Based on Pancharatnam–Berry phase and by careful design of a spatially linear phase profile, it is shown that the amplitude of anomalously refracted circularly cross‐polarized terahertz waves can be effectively modulated by an applied gate voltage. The developed electrically tunable graphene metasurfaces may lead to various advanced applications that require dynamical control over electromagnetic waves, such as amplitude tunable active focusing lenses, vortex phase plates and dynamic holography. [ABSTRACT FROM AUTHOR]

Metamaterials, artificially engineered materials consisting of subwavelength unit cells, have shown potentials in light manipulation with their extraordinary optical properties. Especially, photonic topological metamaterials possessing topologically protected surface states enable extremely robust control of light. Here, an extremely broadband topological phase in photonic topological metamaterials is demonstrated. In particular, topological surface states are observed for all the frequencies below a certain cut‐off, originating from a double Weyl point at zero frequency. The extreme bandwidth and robustness of the photonic topological metamaterial are beneficial for practical applications such as one‐way waveguide and photonic integrated systems but also advantageous in design and fabrication since the only necessary condition is to satisfy the effective hyperbolic and chiral properties, without entailing strict periodic arrangement. [ABSTRACT FROM AUTHOR]