Figure 5. Effective index of refraction of a metamaterial built with Ag@Si core-shell nanowires with R_int = 80 nm and R_out = 170 nm arranged in a hexagonal lattice.

Lower Panel: Retrieved real part of the index of refraction. The blue discontinuous curve represents the values obtained from complex reflection and transmission coefficients under normal incidence. Black circles represent the retrieved values from Snell's law in the prism configuration. The incidence angle is fixed, θ_i = θ_prism = 30°. The corresponding inset shows the y-component of the electric field (only non-zero of the incident wave) for the particular case λ ~ 1215 nm. Red and green squares represent the values obtained from Snell's law in the slab configuration. Angles of incidence are θ_i = 20° (red) and θ_i = 30° (green). The corresponding inset represents the x-component (parallel to the first interface) of the electric field for λ ~ 1215 nm. Error bars computed assuming a systematic error in the determination of the refracted angle of ±2°. Upper Panel: Imaginary part of the index of refraction obtained from complex reflection and transmission coefficients (black curve) and the corresponding figure of merit, f.o.m., as defined in the text (blue curve).