石墨烯超表面对空间波束调控的研究
发布时间：2018-09-12 09:02
【摘要】：石墨烯(Graphene)是一种由碳原子以sp2杂化轨道形成六角碳环的单原子厚度的二维材料。作为一种新型二维材料,它具有极高的电子迁移率,较好的透光率和机械强度。石墨烯在太赫兹和中远红外波段具有负的介电常数,能很好地支持等离子体谐振。石墨烯等离子体谐振与入射波之间的相互作用能改变电磁波的电磁特性,因此周期性图案化的石墨烯结构可以作为超表面的单元结构对空间波束进行调控。石墨烯的电导率具有可调性,能够通过外加电压等方式改变超表面的特性。本文从理论上研究了石墨烯超表面对空间波束的调控。本论文的主要研究内容安排如下:1.石墨烯的结构特性和石墨烯等离子体谐振的简介;对目前超表面和石墨烯超表面的研究进展的综述。2.研究了石墨烯的电磁特性——复表面电导率以及其在不同情况下的化简形式;给出了石墨烯电导率的三种不同的调控方式;对石墨烯进行准确电磁建模并推导得到石墨烯的等效介电常数和表面阻抗。3.提出了能实现极化无关透明窗口的石墨烯互补超表面结构。利用参数分析和数值模拟相结合的方法,给出了透明窗口产生的物理机理。讨论了透明窗口的动态调控效果和窗口频率附近的慢光效应。4.开展了石墨烯超表面对空间波前调控的研究。根据费马原理得到了二维异常透反射的公式;提出了能实现二维异常反射的石墨烯超表面结构;结合涡旋波和梯度超表面的概念,设计了能够产生具有不同模式的涡旋波的石墨烯超表面。
[Abstract]:Graphene (Graphene) is a two-dimensional material with the thickness of a single atom formed by carbon atoms in sp2 hybrid orbitals to form hexagonal carbon rings. As a new two-dimensional material, it has high electron mobility, good transmittance and mechanical strength. Graphene has negative dielectric constant in terahertz and far-infrared band, which can support plasma resonance well. The interaction between graphene plasma resonance and incident wave can change the electromagnetic characteristics of electromagnetic wave, so the periodically patterned graphene structure can be used as a supersurface element structure to regulate the spatial beam. The conductivity of graphene is adjustable and can change the properties of supersurface by means of applied voltage. In this paper, the control of space beam by graphene supersurface is studied theoretically. The main research contents of this thesis are as follows: 1. A brief introduction to the structure of graphene and the plasma resonance of graphene. The electromagnetic charateristics of graphene, the complex surface conductivity and its simplified form under different conditions, are studied, and three different ways of controlling the conductivity of graphene are given. The equivalent dielectric constant and surface impedance of graphene were derived from the accurate electromagnetic modeling of graphene. The complementary supersurface structure of graphene which can realize polarization-independent transparent window is proposed. The physical mechanism of transparent window is given by using the method of parameter analysis and numerical simulation. The dynamic control effect of the transparent window and the slow light effect near the frequency of the window are discussed. The study on the spatial wave front regulation of graphene supersurface was carried out. According to Fermat's principle, the formula of two-dimensional abnormal reflection is obtained, the graphene supersurface structure which can realize two-dimensional abnormal reflection is proposed, and the concepts of vortex wave and gradient supersurface are combined. A graphene supersurface was designed to produce vortex waves of different modes.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71
，
本文编号：2238539
[Abstract]:Graphene (Graphene) is a two-dimensional material with the thickness of a single atom formed by carbon atoms in sp2 hybrid orbitals to form hexagonal carbon rings. As a new two-dimensional material, it has high electron mobility, good transmittance and mechanical strength. Graphene has negative dielectric constant in terahertz and far-infrared band, which can support plasma resonance well. The interaction between graphene plasma resonance and incident wave can change the electromagnetic characteristics of electromagnetic wave, so the periodically patterned graphene structure can be used as a supersurface element structure to regulate the spatial beam. The conductivity of graphene is adjustable and can change the properties of supersurface by means of applied voltage. In this paper, the control of space beam by graphene supersurface is studied theoretically. The main research contents of this thesis are as follows: 1. A brief introduction to the structure of graphene and the plasma resonance of graphene. The electromagnetic charateristics of graphene, the complex surface conductivity and its simplified form under different conditions, are studied, and three different ways of controlling the conductivity of graphene are given. The equivalent dielectric constant and surface impedance of graphene were derived from the accurate electromagnetic modeling of graphene. The complementary supersurface structure of graphene which can realize polarization-independent transparent window is proposed. The physical mechanism of transparent window is given by using the method of parameter analysis and numerical simulation. The dynamic control effect of the transparent window and the slow light effect near the frequency of the window are discussed. The study on the spatial wave front regulation of graphene supersurface was carried out. According to Fermat's principle, the formula of two-dimensional abnormal reflection is obtained, the graphene supersurface structure which can realize two-dimensional abnormal reflection is proposed, and the concepts of vortex wave and gradient supersurface are combined. A graphene supersurface was designed to produce vortex waves of different modes.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71
，
本文编号：2238539
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