Analysis of polarization transformations by a planar chiral array of complex-shaped particles

Vectorial relations of field amplitudes are derived from the Lorentz lemma applied to electromagnetic fields at direct and reversed scenarios of a wave diffraction on a doubly-periodic planar array. Biorthogonality of polarization eigenstates of the waves propagating in opposite directions is shown with reference to a wave channel formed by an incident wave and a diffraction order. For a planar chiral array, an essential difference in polarization transformations of propagated waves is ascertained in the direct wave channel and in the reversed one. Numerical data are presented to demonstrate the polarization transformations by both transmitting and reflecting planar chiral arrays. A difference in polarization eigenstates inherent to a planar chiral array and a bulk chiral medium is noticed.