Discovery

Last month, the researchers from Harald Giessen at the University of Stuttgart succeded in manufacturing a stacked split-ring metamaterial for the optical wavelength range. This layer-by-layer stacking procedure is capable of producing well aligned three-dimensional metamaterial structures.

Before, researchers from Duke University stunned the world when they announced a cloaking device for the microwave range. The key to this achievement was a planarization method for the rough nanolithography surface in combination with robust alignment marks which survived the dry etching processes during nanofabrication.

The present 3D structures consist of horseshoe-shaped gold nanowires that are arranged in a square pattern and perfectly stacked above each other. Due to the strong vertical coupling, broadband optical features arise. Also, the vertical coupling leads to negative permeability of the structure, which is a prerequisite for a negative refractive index.

Adapted from materials provided by University of Stuttgart.