Polarization independence of extraordinary transmission trough 1D metallic gratings

Extraordinary optical transmission of 1D metallic gratings is studied. Experimental samples are fabricated by means of Electron Beam Lithography. The optical characterization is focused on far field transmission properties and in particular on polarization dependence of the incident light. A peculiar symmetry in transmission spectra at different polarization angles is shown; this symmetry is studied both experimentally, and numerically with FEM method. A comparison between numerical and experimental data is provided.