Experimental demonstration of sidewall angle induced bianisotropy in multiple layer negative index metamaterials

The effect of a nonzero sidewall angle on the performance of multiple layer fishnet-structure (one to three functional layers) negative index metamaterials is evaluated experimentally. The fabrication-induced sidewall angle results in a bianisotropy (inhomogeneous asymmetry) that is significant at optical frequencies. Good agreement is obtained between the experimental transmission and reflectance measurements and the simulation results. Modifications to the standard parameter retrieval algorithm are discussed.