Double negative in flexural single metal layer at visible frequencies

We theoretically investigate a thin single metal layer covered on sub-wavelength dielectric grating. Numerical simulations show that the structure has negative index in the normal direction at visible frequencies. Structural investigation demonstrates that the simultaneous negative permittivity and permeability at an overlapping frequency range are attributed to the metal cut-wire and “U”-shaped structure disassembled from the structure, respectively. Furthermore, parametric exploration for practical fabrication is presented.