Research On The Nonlinear Electromagnetic Properties And Simulation Method Of Metamaterials

In the early sixties of the twentieth century, the electrical dynamics properties of the materials with simultaneously negative permittivity and negative permeability were proposed theoretically by a physicist of ex-Soviet Socialism Public Union Veselago, the unusual features of this kind of materials, such as reversed Doppler effect, reversed Vavilov-Cerenkov radiation effect, negative optical pressure and reversed Snell'law as well as the phenomena of perfect lens, reversal of convergence and divergence in convex and concave lenses, etc were predicted, which becomes the prelude of metamaterials research. In recent decades, the investigation actives become one of the hot spot of international scientific research and lots of surprising progresses have been made because of the unusual properties of metamaterials and their huge and wide potential applications. At present, the mostly concerned research hot spots include the deepened and broadened study of nonlinear properties of metamaterials, design and fabrication technologies of optical metamaterials, the movement of the response frequency of the electromagnetic parameters towards visible band and their expansion, the improvement of computer simulation techniques, etc.In view of the situation mentioned above, the nonlinear properties of metamaterials based on wires and split ring resonators are investigated:the nonlinear features of effective permittivity of this metamaterial is calculated, the variation of the attribute of the material along with the change of external electromagnetic field is studied considering the changes of the permittivity and permeability with varying incident field. The results show that the electric permittivity has hysteresis characteristics, and under some different conditions, the attribute of the metamaterials can jump among double positive materials, epsilon-negative materials and mu-negative materials. These results verify the conclusions based on a hypothesis in the paper of Zharov, at the same time, the results also correct the incompleteness of Zharov's conclusions.Besides, the author of this dissertation also did some research into the computer simulation methods of metamaterials. The results including the modeling of negative refraction phenomenon in double negative materials, the imaging in perfect lens and the propagation of electromagnetic waves in cascade waveguide are reported in the corresponding chapter. These simulations can show some visual interpretations views of the phenomena happened in metamaterials.