Planar metamaterial with transmission and reflection that depend on the   direction of incidence
  We report that normal incidence reflection and transmission of circularly polarized electromagnetic waves from and through planar split-ring metamaterials with chiral symmetry breaking depends on the incidence direction and handedness of circular polarization. The effect has a resonant nature and is linked to the lack of mirror-symmetry in the metamaterial pattern leading to a polarization-sensitive excitation of electric and magnetic dipolar responses in the meta-molecules. 
E. Plum, V. A. Fedotov, N. I. Zheludev