Metamaterials in waveguide geometries

Most state-of-the-art optical metamaterials are thin layers of functionalized plasmonic nanostructures of certain geometries. To enhance the understanding how such systems can be used in waveguide geometries, the authors investigate the interaction of a dielectric waveguide with the plasmonic nanostructures. A double cut-wire on top of a slab waveguide was chosen as a model system consisting of a 350 nm thick layer of Si₃N₄ on a fused silica substrate. Since the waveguide is terminated by air, its refractive index profile is highly asymmetric. Hence, the fundamental transverse magnetic mode possesses a relatively strong electric field component in propagation direction. This configuration allows to probe plasmonic eigenmodes of the double cut-wire.