Numerical Study of an Efficient Broadband Metamaterial Absorber in Visible Light Region

We report a numerical study of a broadband metamaterial absorber in visible light region by utilizing a single layer of metal-dielectric-metal configuration. The absorption bandwidth and absorption performances are tailored by varying the resonator shapes and metal materials. The absorption bandwidth of the proposed metamaterial absorber (MA) structure is enhanced significantly with decreasing the order of rotational symmetry of the resonator shape. Using gold configuration, the twofold symmetry MA structure based on the double-sized axe shaped resonator exhibits the broadband absorption response over the entire visible light and apart of infrared spectrum range from 320 to 982 nm with absorptivity above 90% for both transverse electric and transverse magnetic polarizations. The physical mechanism of broadband absorption is explained by the current, electric, and magnetic distributions, significantly affected by the propagating surface and localized surface plasmon resonances. Furthermore, the high absorber performances of the twofold symmetry MA structure can be obtained over entire visible light region (400-700 nm) for both noble metal of gold and low-cost metal of nickel configurations, indicating the proposed absorber is a promising candidate for low-cost and large-scale fabricate device operated in visible light region.