Asymmetric Transmission in Diffractive Chiral Metasurfaces Consisting of Nanoantennas

We have studied the asymmetric transmission in diffractive chiral metasurfaces  consisting of nanoantennas. The study was made of lattice plasmon modes on the  phenomenon of asymmetric transmission in chiral two dimensional arrays of  plasmonic nanoparticles. It was demonstrated that asymmetric transmission resulted  from contribution of higher order diffracted waves. It was shown that the isolated  nanostructures has a fourfold rotational symmetry, the diffractive metasurfaces  exhibited asymmetric transmission for normal incidence light within spectral range for  which lattice plasmon modes were supported. It was found that lattice plasmon modes  played role in enabling symmetric transmission in diffractive chiral metasurfaces. The  symmetric transmission mechanism is due to different lattice plasmon mode excitation  efficiencies of left circularly polarized and right circularly polarized and right circularly  polarized light. The excitation efficiencies are controlled by tailoring the nano particles  in plan distribution of scattered light for circularly polarized excitation and its  alignment with the inplane diffraction orders of the metasurfaces. The phenomenon for  a metasurface composed of an array of a chiral nanoparticles consisting of four  nanoantennas. It was shown that the Rayleigh anomaly condition where the  asymmetric transmission effect was strongest and metasurfaces supported lattice  plasmon modes. It was found that the difference in the inplane scattered intensity  varied as a function of the inplane angle around the nanostructure, rotating the  nanostructure in the plane of the metasurface. The obtained results found in good  agreement with previously obtained results.