Polarization independent metallic-dielectric trapezoidal grating for multiband absorption in the visible

We propose and analyze in details a selective multiband absorber with polarization-independent behavior based on a metal/dielectric periodic grating with trapezoidal cross section operating for visible light frequencies. The absorption near unity for independently polarized waves is observed for a normal incidence in all absorption peaks. The physical mechanisms of the narrowband selective absorber are investigated and explained by the spatial distribution of the electromagnetic fields of the structure for each resonant peak. The behavior of the structure for obliquous incidence is also analyzed and the structure maintained high absorption for both modes of polarization for incident angles of up to 10^°. The dependence of the absorber is also analyzed by sweeping the optical and geometrical parameters of the grating.