超材料表面波特性的研究

发布时间：2018-11-10 19:08

【摘要】：表面波是指被限制在两种介质的一个很薄的界面区域内并沿这个平面方向传播的电磁波,在垂直于这个平面方向上,其振幅会随着偏离平面距离的增加而逐渐衰减。超材料(metamaterial)是具有天然材料所不具备的超常物理性质的人工复合结构或复合材料,在电磁隐身、完美透镜和超分辨成像等领域具有重要的应用。由于超材料具备新颖的物理性质,在其表面传播的表面波的性质也自然地引起了人们的关注。目前人们主要通过对超材料结构的设计来调控超材料表面波,然而一旦其结构被设计好之后便无法改变,因此研究对表面波进行调控具有更重要的意义。本论文主要研究了通过施加外物理场调谐超材料表面波的特性。具体的研究内容和结果如下:1.非线性超材料与超导材料界面处的表面波研究了非线性超材料与超导材料界面处的非线性TE表面波,基于界面处电磁场的连续性,获得了非线性表面波的色散方程。运用了二流体模型讨论了温度对于高温超导体的介电常数的影响,数值计算并讨论了表面波传播的等效折射率、能流分布、非线性超材料中孤子场分布最大值的位置等。结果表明等效折射率(表面波的传播速度)的大小和孤子振幅最大值的位置可以受到温度和非线性项的调谐。孤子峰值的位置随着非线性项的不断增大而靠近分界面,随着温度不断增大而远离界面。表面波能量主要以孤子的形态分布在非线性材料中,通过改变温度可以来调谐表面波在两种介质中的能流分布。2.外磁场对介于半导体与超材料界面处表面波的调控研究了介于超材料和半导体材料界面处的非线性TE表面波,获得了表面波的色散关系。基于半导体In Sb磁光沃伊特效应,数值计算并讨论了外磁场和非线性项对等效折射率、能流分布、孤子振幅最大值位置的调控。结果表明当频率小于半导体的等离子频率时,等效折射率随着外磁场的增大而增大,而当频率大于半导体的等离子频率时,等效折射率随着外磁场的不断增大而减小。等效折射率随着非线性项增强而不断增大。孤子的峰值位置随外磁场增大和非线性项增强而靠近分界面。通过改变外磁场来调谐表面波能量在两种介质中的分布,结果可应用于光隔离器。3.介于非线性材料与超材料界面处的表面波研究了介于非线性材料与线性超材料界面处的非线性TM表面波的精确色散特性。TM波是两个电场分量相互耦合的矢量表面波,通过一次积分方法获得非线性表面波精确的色散关系。近似线性解与精确的色散关系进行比较发现色散关系曲线的在讨论的频率范围内偏离10%以上。在此基础上我们讨论了等效介电常数、表面波的穿透深度随着激发电磁波场强度和非线性介质的克尔系数变化的规律。
[Abstract]:Surface wave is a kind of electromagnetic wave which is confined in a very thin boundary area of two kinds of media and propagates along the plane direction. In the vertical direction of the plane, the amplitude of the wave decreases gradually with the increase of the distance away from the plane. Metamaterial (metamaterial) is an artificial composite structure or composite material with supernormal physical properties which is not possessed by natural materials. It has important applications in electromagnetic stealth, perfect lens and super-resolution imaging. Due to the novel physical properties of metamaterials, the properties of surface waves propagating on their surfaces have naturally attracted people's attention. At present, the design of metamaterial structure is mainly used to control the metamaterial surface wave, but once its structure is designed, it can not be changed, so it is more important to study the regulation of the surface wave. In this paper, the characteristics of surface waves of metamaterials tuned by external physical field are studied. The specific research contents and results are as follows: 1. The nonlinear TE surface wave at the interface of nonlinear supermaterial and superconducting material is studied. Based on the continuity of electromagnetic field at the interface, the dispersion equation of nonlinear surface wave is obtained. The influence of temperature on the dielectric constant of high temperature superconductors is discussed by using a two-fluid model. The equivalent refractive index of surface wave propagation, the energy flow distribution and the position of the maximum soliton field distribution in nonlinear supermaterials are numerically calculated and discussed. The results show that the magnitude of the equivalent refractive index (the propagation velocity of the surface wave) and the position of the maximum soliton amplitude can be tuned by the temperature and the nonlinear term. The position of the soliton peak value is close to the interface with the increasing of the nonlinear term and far away from the interface with the increase of temperature. Surface wave energy is mainly distributed in nonlinear material as soliton, and the energy flow distribution of surface wave in two media can be tuned by changing temperature. 2. The nonlinear TE surface waves at the interface between the supermaterial and the semiconductor material are studied by the external magnetic field. The dispersion relationship of the surface waves is obtained. Based on the In Sb magneto-optical Woithe effect, the control of the external magnetic field and nonlinear terms on the equivalent refractive index, energy flow distribution and the position of the maximum soliton amplitude is numerically calculated and discussed. The results show that the equivalent refractive index increases with the increase of the external magnetic field when the frequency is less than the plasma frequency of the semiconductor, while the equivalent refractive index decreases with the increasing of the external magnetic field when the frequency is larger than the plasma frequency of the semiconductor. The equivalent refractive index increases with the increase of nonlinear term. The peak position of the soliton is close to the interface with the increase of the external magnetic field and the enhancement of the nonlinear term. The distribution of surface wave energy in two media can be tuned by changing the external magnetic field. The results can be applied to the optical isolator. The exact dispersion of nonlinear TM surface waves at the interface between nonlinear material and metamaterial is studied. TM wave is a vector surface wave coupled with two electric field components. The exact dispersion relation of nonlinear surface waves is obtained by the one-order integral method. By comparing the approximate linear solution with the exact dispersion relation, it is found that the dispersion curve deviates by more than 10% in the frequency range under discussion. On this basis, we discuss the law of the change of equivalent dielectric constant, penetration depth of surface wave with the intensity of excited electromagnetic wave field and Kerr coefficient of nonlinear medium.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O441.4;TB39

【相似文献】