Ultrathin metasurfaces have recently emerged as promising materials to enablenovel, flat optical components and surface-confined, miniature photonicdevices. However, experimental realization of high-performance metasurfaces atvisible frequencies has been a significant challenge due to high plasmoniclosses and difficulties in high-uniformity nanofabrication. Here, we propose ahighly-efficient yet simple metasurface design comprising of single gradientantenna as unit cell. We demonstrate visible broadband (450 - 850 nm) anomalousreflection and spectrum splitting with 85% conversion efficiency. Average powerratio of anomalous reflection to the strongest diffraction was calculated to be~ 103 and measured to be ~ 10. The anomalous reflected photons and spectrumsplitting performance have been visualized using CCD and characterized usingangle-resolved measurement setup. Metasurface design proposed here is a cleardeparture from conventional metasurfaces utilizing multiple, anisotropicresonators, and could enable high-efficiency, broadband metasurfaces forachieving directional emitters, polarization/spectrum splitting surfaces forspectroscopy and photovoltaics.
展开▼
