Experimental verification of substrate-induced bianisotropy in optical metamaterials

In this paper, we experimentally prove the theory that the supporting substrate underneath metallodielectric optical metamaterials induces bianisotropy due to the broken symmetry of the system. Specifically, an on-wafer fishnet structured metamaterial at near-infrared wavelengths was fabricated and fully characterized. The effective medium parameters extracted from the experimental data agree well with the theoretical predictions, thus confirming the existence of magnetoelectric coupling introduced by the substrate, which is otherwise absent in a free-standing fishnet metamaterial with the same dimensions. This study provides engineers and scientists insight into oft-overlooked properties of optical metamaterials.