Super Diffraction in a Single-Layer Metasurface

We suggest that super diffraction of light can be realized with a planar plasmonic metasurface, i.e., a single-layer metal surface with super-wavelength asymmetric grooves. The structure of the system is simple and easy to be fabricated in experiments. The efficiency of + 1st-order diffraction of the carefully designed metasurface is higher than 50% over a broadband width of over 1350 nm in the near infrared regime while -1st-order diffraction and the 0th-order reflection are suppressed. The physical mechanism of the anomalous diffractions can be attributed to the collective effect of single grooves in the metasurface. The design may have important applications in the beam splitters, spectroscopy studies, and thin-film solar cells.