Broadband Transformation Optics Devices
Current interest in electromagnetic meta-materials has been motivated by recent work on superlenses, cloaking and transformation optics. This interest has been followed by considerable efforts aimed at introduction of meta-material structures that could be realized experimentally. Unfortunately, it appears difficult to develop meta-materials with low-loss, broadband performance. The difficulties are especially severe in the visible frequency range where good magnetic performance is limited. On the other hand, very recently the authors have demonstrated that many transformation optics and meta-material based devices requiring anisotropic dielectric permittivity and magnetic permeability could be emulated by specially designed tapered waveguides. This approach leads to low-loss, broadband performance in the visible frequency range, which is difficult to achieve by other means.