| Transformation optics, also termed as optical transformations, which is based on the form-invariance of Maxwell’s equations under coordinate transformations, provides an extremely intuitive and visual approach to manipulate the electromagnetic waves for different requirements of the specifications. An electromagnetic device can be designed by choosing an appropriate coordinate transformation, and the constitutive parameters of the device can be determined by transformation optics. The electromagnetic phenomenon in the transformed space with the transformed media is extremely the same as the original space. The electromagnetic invisibility cloak which is based on transformation optics was proposed and experimented in microwave frequencies, and transformation optics attracted more and more attentions in the past few years. Based on this novel concept, cloaks with different geometries or methods have been proposed, and a number of new devices emerged.With this background, in this dissertation, the development of the electromagnetic metamaterials and transformation optics has been introduced firstly. Besides, we have introduced the left-handed materials and the theory of transformation optics in detail. This dissertation proposed and carefully studied some new electromagnetic devices based on transformation optics and the complementary media. And the main work and contributions of this dissertation are listed below:1. An electromagnetic cloak with opened information has been proposed. With introducing a layer of complementary media between the electromagnetic invisibility cloak and the shielded object, the electromagnetic wave can penetrate into the shielded region, which means that the shielded effect of information for the object has been broken, and the object can be invisible to the detector while can receive or transmit signals. Full wave simulation results and Mie scattering theory have demonstrated the perfectness of the cloak. Furthermore, this method has been expanded to the cylindrical cloaks with arbitrary geometries, and the constitutive parameter equations of the cloak with and without conformal boundaries have been deduced and demonstrated by the simulaed results.2. The constitutive parameter equations of the external cloaks with arbitrary geometries have been deduced, and the conformal "anti-object" of the object has been used to cloak multi-objects outside the cloak. The external cloak has a smaller size compared with the traditional inner cloak. In addition, a combined cloak and an inner-outer cloak which are based on the circular external cloak have been proposed. The combined cloak has simple parameters, and the inner-out cloak can cloak objects inside and outside the cloak at the same time. The parameter equations have been expanded to three-dimensional external cloak with arbitrary geometries, and simulation results and Mie scattering theory demonstrate the perfectness of the spherical external cloak.3. Two devices have been proposed to change the scattering mode of objects. First, the scattering controller can amplify or decrease the scattering cross sections of PEC, or imitate the scattering mode of different PECs with arbitraty geometries. Second, the illusion device can turn the scattering mode of a dielectric into the scattering mode of other dielectrics or metals. The parameter equations of the illusion device with arbitrary geometries have been deduced. Furthermore, a square device, which is consisted of four triangular illusion devieces, can partially cloak the inner dielectric and produce different scattering modes.4. The multi-functional electromagnetic concentrator, which is based on the optical transformations and complementary media, has been proposed and the parameter equations of the concentrator with arbitrary geometries have been deduced. The multi-functional concentrator can concentrate the electromagnetic fields and energy into the compressed regions. Additionally, the concentrator can cloak the object outside, amplify the scattering cross section of the object in the core layer, create an illusion effect and so on. The multi-functional concentrator has a smaller size compared with the traditional concentrator which is based on transformation optics. Otherwise, the analysis for the electromagnetic fields demonstrated the concentrating effect of the multi-functional concentrator. |
