Super-Resolution Focusing Using Volumetric, Broadband NRI Media

We describe the design, fabrication and testing of broadband negative permeability and broadband negative-refractive-index (NRI) metamaterials. The NRI metamaterial is designed to address two major limitations of current NRI media: high loss and narrow bandwidth of operation. The proposed NRI design has a backward-wave bandwidth of 44.3%. This large bandwidth allows the structure to operate away from resonant frequencies, where the loss is significantly lower. The stopband characteristics of a lambda₀/3 slab of the negative permeability medium were measured. In addition, the focusing characteristics of the NRI medium were tested and resolution beyond the diffraction limit was experimentally observed. The slab measured in this paper achieved a resolution enhancement of 2.0 over a bandwidth of 0.33%.