Multiband plasmonic absorber based on transverse phase resonances.

We demonstrate a multiband plasmonic absorber based on transverse phase resonances. We show that the modification of conventional metallic surfaces of T-shape grooves can cause mode splitting of the plasmonic waveguide cavity modes due to lattice scattering and all the new resonant modes exhibit large absorbtivity greater than 90%. Some of the generated absorption peaks have wide-angle characteristics. Furthermore, we find that the proposed structure is fairly insensitive to the alignment error between different layers.