Direction-selective waveguide of a two-layer silver film with angled holes

Using the discrete dipole approximation (DDA) method, we investigated the propagation of light within the visible wavelength region for a two-layer silver film with periodic angled holes. The perforation of the holes at an angle of 45 allows light to propagate selectively along different directions at two resonance wavelengths. The Poynting vector calculations show that light propagating along the direction of hole perforation at shorter wavelengths is due to the coupling between periodic holes, while the other one along the opposite direction at longer wavelengths is related to the coupling between the top and bottom layers in the film.