Dual-band nearly perfect absorber at visible frequencies

In this paper, we propose and demonstrate a dual-band metamaterial absorber at normal incidence based on a five-layer metal-insulator-metal (MIM) stacked structure. The designed structure exhibits two peaks with over 95% absorption efficiency in the visible region. The physical mechanism of two absorption peaks is systematically investigated by the anti-symmetric and symmetric modes in the multilayer structure. As demonstrated in the calculation and experiment, two absorption peaks demonstrate well scalability with the change of structure periodicity. We envision this nearly perfect absorber would find great potential in the high performance photovoltaics and thermal emitter devices.