Optical Properties of Layered Metamaterial Composed of Pairs of Nanowires

A metamaterial composed of electromagnetically active cells with two parallel wires of sub-wavelength size can be fabricated by means of patterning techniques used in microelectronics. Intensity transmittance of layered metamaterial is assessed as a function of fill factor, that is a ratio of wire to layer surfaces, that in simulations changes from 6 to 20%. Negative refractive index reaching as low as -0.5 is predicted in the range of 1.13-1.29 mum for fill factor 12%. Then in FDTD simulations we analyze propagation of light through single and multiple layers of the metamaterial. A single layer exhibits a negative index of refraction at wavelengths for which absorption results from a high imaginary value of n. FDTD simulations show that the negative n should appear for the range of 1.92-2.19 mum. Theoretical underassessment of the range of wavelengths where n is negative comes from simplicity of the considered dipole model. We conclude that the smaller is the fill factor, the narrower the range of frequencies, where n is negative. Then, the smaller is the fill factor, the less negative is n. Finally, transmission considerably decreases with increasing fill factor