Angle-selective chiral absorption induced by diffractive coupling in metasurfaces.

Here we report that a simple chiral metasurface with twisted metallic cut-wire arrays enables highly efficient and continuously tunable chiral absorption over a broad spectral range by scanning the incidence angle over a few degrees. The angle-selective chiral absorption results from the surface plasmon resonance (SPR) excited by diffractive effects of the metasurface. The diffraction-assisted chiral metasurface provides a straightforward strategy for achieving dynamically tunable chiral devices and offers intriguing possibilities for various applications in on-chip chiral detectors/emitters, chiral spectrometers, chiral lasers, and so on.