Helical Metamaterial Absorbers: Broadband and Polarization-Independent in Optical Region

We propose a design of a novel optical metamaterial absorber that is broadband and independent to polarization. The absorber consists of opposite-handedness metallic triple-helix array. Simulated by the finite-difference time-domain (FDTD) method, an average absorbance of 89.10% is observed in the region of 0.33-1.22 μm as well as an absorption peak of 97.57% at 0.43 μ m. Compared with many existing planar metamaterial absorbers, this helical metamaterial absorber shows advantages of broadband and polarization independence. In addition, we systematically study the dependence of the absorptive property on its geometric parameters and materials. It is expected that the superior absorptive properties of this helical MM absorber can also be realized in other region of spectrum by appropriately scaling the sub-wavelength structures.