All-Dielectric Perfect Absorber of Quadrupole Modes by using Cross-Shaped Mie Resonators

To overcome the absorption limit of an ultra-thin layer, all-dielectric perfect absorbers of dipole modes can be realized based on degenerate critical coupling. Here, we propose theoretically a cross-shaped silicon perfect absorber of quadrupole modes in the visible region and demonstrate that the degenerate critical coupling applies to higher-order modes.