Ultra-thin metamaterial absorber with extremely bandwidth for solar cell and sensing applications in visible region

• We proposed a broadband and ultra-thin metamaterial absorber in the visible region.
• Numerical results reveal that a broadband absorption spectrum above 90% can be realized from 353.9 THz to 613.2 THz due to the coupling effect between the material of stannum and InSb.
• The metamaterial absorber is ultra-thin, having the total thickness of 56 nm, i.e. less than λ/10 with respect to the center frequency of the absorption band more than 90%.
• The sensing applications are discussed and the simulation results show that the proposed absorber operates well with a good efficiency.

In this paper, we proposed a broadband and ultra-thin metamaterial absorber in the visible region. The absorber is composed of three layers, and the most remarkable difference is that the split ring resonators (SRR) made of metal stannum are encrusted in the indium antimonide (InSb) plane on the top layer. Numerical results reveal that a broadband absorption spectrum above 90% can be realized from 353.9 THz to 613.2 THz due to the coupling effect between the material of stannum and InSb. The metamaterial absorber is ultra-thin, having the total thickness of 56 nm, i.e. less than λ/10 with respect to the center frequency of the absorption band more than 90%. In addition, the impedance matching theory, surface current distributions, E-field and H-field are investigated to explain the physical mechanism of the absorption. The sensing applications are discussed and the simulated results show that the proposed absorber operates well with a good efficiency. Moreover, the visible absorber has potential applications in the aspects of solar energy harvest, integrated photodetectors and so on.