Anomalous diffraction in super-wavelength plasmonic metasurfaces

We demonstrate that super-wavelength sandwich plasmonic metasurfaces, with the top metal layer consisting of a periodic arrangement of differently sized rectangle patches, can support anomalous diffraction - one first-order diffraction is boosted greatly in a broad bandwidth while another first-order and zero-order diffractions are suppressed. More importantly, by adding and subtracting the patches in a unit cell and adjusting the geometric parameters, high efficiency and broadband first-order diffraction can be easily tuned from visible to near-, mid- and even far-infrared spectral regions. The metasurfaces can be applied as high-performance light dispersive components in beam splitters, thin-film solar cells and spectrometers.