Negative real parts of the equivalent permittivity, permeability, and refractive index of sculptured-nanorod arrays of silver

Thin films comprising parallel nanorods were deposited by directing silver vapor obliquely toward a plane substrate. The direction of the vapor flux was varied in two different ways to sculpture the nanorods in different shapes. The reflection and transmission coefficients of the thin films were measured at three wavelengths in the visible regime for normal-illumination conditions for two linear-polarization states, using walk-off interferometry and polarization interferometry. The authors found that sculpturing significantly affects the signs of the real parts of the equivalent permittivity, permeability, and refractive index of the silver thin films for the two polarization states at different wavelengths. Thus, vapor deposition combined with sculpturing can be useful for large-scale production of materials having different equivalent constitutive parameters with negative real parts.