Double-element metamaterial with negative index at near-infrared wavelengths

We present the realization of a metamaterial that combines double cut wires and continuous wires in its unit cell. This double-element geometry together with the applied layer-by-layer fabrication technique permits an independent tuning of the geometry of the unit-cell components. The characterization of the samples is based on the measurement of transmission and reflection spectra combined with rigorous numerical simulations. The results show that the metamaterial exhibits an effective refractive index of n=-0.5+1.9i at the wavelength lambda = 2.1 mu m.