Transformation Optical Design Of A Bending Waveguide By Use Of Isotropic Materials

This article is based on transformation optics and effective media theory. We design a method to simplified transformation bending waveguide. In this method, we only need three kinds of isotropic materials. With these materials, we can smoothly guide the light in the waveguide with only little distortion. Transformation optics is that when we do the transformation in different spaces, we keep the same material properties(ε,μ) unchanged but change the space coordinates. But if we considered from the opposite side, we keep the transformation in the same coordinate but change the property of the materials(ε,μ), the same miracle will happen. That means the two transformations are the same. Based on this theory, we can control electromagnetic field at our pleasure in cartesian coordinates. One example for it is invisible cloak. But one of most important problem behind the fantasy is that we don't have whatever electromagnetic materials with variesεandμwe want by now, but we need to get exactεandμat every points in the space. Actually, the electromagnetic materials are very limited to us. This is a challenge for experiments and application, but our pioneer job is to make it to reality. Because isotropic materials are easy to find and get in nature, this will help us greatly reduce the difficulty of experiments. At the end of the article, we give our numerical simulation to show its effect is well match the perfect simulation.