Stereometamaterials

The subdiscipline of chemistry that studies molecular structures in three dimensions is called stereochemistry. One important aspect of stereochemistry is stereoisomers: materials with the same chemical formula but different spatial arrangements of atoms within molecules. The relative positions of atoms have great influence on the properties of chemical substances. Here, in analogy to stereoisomers in chemistry, we propose a new concept in nanophotonics, namely stereometamaterials, which refer to metamaterials with the same constituents but different spatial arrangements. As a model system of stereometamaterials, we theoretically and experimentally study meta-dimers, which consist of a stack of two identical split-ring resonators in each unit cell with various twist angles. The interplay of electric and magnetic interactions plays a crucial role for the optical properties. Specifically, the influence of higher-order electric multipoles becomes clearly evident. The twisting of stereometamaterials offers a way to engineer complex plasmonic nanostructures with a tailored electromagnetic response.