Theoretical Design And Simulation Of Transparent Cloaks

In recent years, metamaterials along with transformation optics have become one of the most popular topics in the science and engineering community. The transformation optics method, which is based on forminvariant transformations of Maxwell's equations, is a theory to control the propagation of the electromagnetic field. It has been widely used for the design of metamaterials and novel electromagnetic devices. In this dissertation, we begin with the fundamental principles of transformation optics, and mainly do the research on transparent cloaks. The following aspects are covered.The efficient transformation optics method is utilized to design two-dimensional transparent cloaks with arbitrarily and non-conformal inner and outer boundaries. The general and explicit expressions for the material parameters of the transformed space are derived and analysed. Full-wave simulations are applied to validate the transparency of the cloaks working in gradually changing background and layered media. The simulation results under different circumstances demonstrate that the proposed method is correct and efficient.A classical method based on analytical results and a transformation optics method using an arbitrary piecewise continuous transformation function are applied to design a one-dimensional electromagnetic transparent wall. Material parameters and the geometrical requirement of the layered structure using these two different methods are derived and compared. Full-wave simulations validate the transparency of the proposed wall, a transparent structure realized using anisotropic and homogeneous materials.A new method by solving Helmholtz's equation with certain proposed boundary conditions, is proposed to design the transparent cloak with non-conformal inner and outer boundaries. According to optics transformation, the solution of Helmholtz's equation is used to get the material's electromagnetic parameters in the transformed space, which is defined by the boundaries of Helmholtz's equation. Full-wave simulations further validate the efficiency of the method.The array made of the metal strips with different geometric size is used to design an electromagnetic lens. The equivalent refractive index of the lens is given and analysed by theory of transmission lines. The field distribution of the lens by full-wave simulation demonstrates the field deflection and focusing effect.Our study shows that transformation optics is a powerful tool in the design of the transparent cloaks. In the whole process of the design, the crucial step is to seek the proper transformation functions in order to configure the parameters of the particular medium, i.e. permittivity and permeability, which can be controlled by adjusting its configurations, thus metamaterials. The deep research on the transparent cloak expands the application field of transformation optics, and enriches the content of electromagnetic devices.