贵金属纳米方盘—方框结构高阶表面等离激元共振效应研究

发布时间：2018-01-24 21:12

本文关键词： 表面等离激元表面等离激元共振高阶表面等离激元共振等离激元耦合　出处：《陕西师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：贵金属的表面等离基元是指激发光与金属表面附近的自由电子相互耦合所产生的沿着金属的表面传播的一种电磁波,其理论自上世纪被提出之后获得了越来越广泛的关注。金属纳米颗粒的表面等离激元会随着外部电磁场的改变而发生运动,当表面等离子体和外界电磁场的频率一致时会发生共振,即为表面等离激元共振。金属纳米结构的尺寸以及形貌都会对产生的表面等离激元共振特性构成很大的影响,因此可以通过调整这些参数来构建具有不同光学性质的表面等离基元器件。由于表面等离激元器件可以突破光的衍射极限,从而实现比传统光学器件更高的精度来操作光,所以在很多领域展示出了巨大的应用前景,比如表面增强光谱、等离激元光波导、太阳能电池、以及生物传感器等。随着各种理论研究的逐渐深入以及在微纳尺度下对于金属颗粒进行加工的技术越来越成熟,对于不同的金属纳米结构的表面等离基元性质已经成为了一项非常热门的研究课题。这项研究也形成了一项迅猛发展的新兴学科,即表面等离激元光子学。本文基于表面等离激元光子学的研究现状,针对目前绝大多数的研究都集中在复杂的二维纳米结构,提出了一种通过简单几何结构的耦合来产生比较复杂的表面等离激元特性的方法。本文主要分为三个部分,第一部分对目前主要使用的一些数值计算方法和本文中进行数值计算的软件进行了介绍。第二部分对于一些基本的纳米结构和纳米二聚体的表面等离激元特性进行了介绍。第三部分设计了方框-方盘(SRD)复合结构并研究了其表面等离激元光学特性并着重研究由于破坏对称性而产生的一些高阶表面等离激元共振特性。各部分的内容总体叙述如下；第一部分：介绍了目前常用的的一些数值计算方法,并且对于本文中使用的数值计算软件做以简单介绍。其中主要介绍了时域有限差分(FDTD)法,离散偶极近似(DDA)法,以及有限元(FEM)法这三种常用的数值模拟算法。之后重点介绍了本文中所使用的利用了有限元法的COMSOL Multiphysics软件。对于其中建模时需要注意的一些诸如边界条件的设置、端口的设置和S参数的计算、初始值和背景场的设置等均做了详细的解释。第二部分：研究了一些比较基础的结构的表面等离激元特性。从最简单的纳米球,纳米盘以及纳米环入手。随后介绍了一些有关于纳米颗粒二聚体的表面等离激元特性,其中分别包括了纳米球二聚体和纳米盘二聚体。介绍了一种在二聚体中产生暗等离激元共振模式的方法。第三部分：设计了一个方框-方盘(SRD)结构,通过改变SRD结构中方盘和方框的相对位置来获得不同程度的不对称性,从而来调节方框的表面等离激元共振模式,产生高阶振动模式或者补全一些在对称的结构下无法被激发出来的共振级次。
[Abstract]:The surface isodissociation of precious metals is a kind of electromagnetic wave propagating along the surface of metals which is generated by the coupling of light and free electrons near the metal surface. Since its theory was put forward in the last century, more and more attention has been paid to it. The surface isotherms of metal nanoparticles will move with the change of external electromagnetic field. Resonance occurs when the frequency of the surface plasma is the same as that of the external electromagnetic field. The size and morphology of metal nanostructures have a great influence on the resonance characteristics of surface isoexcitators. Therefore, we can adjust these parameters to construct the surface equidistant components with different optical properties, which can break through the diffraction limit of light. In order to achieve higher precision than the traditional optical devices to operate light, so in many fields have shown great application prospects, such as surface enhanced spectra, isobaric optical waveguides, solar cells. As well as biosensors and so on. With the gradual deepening of various theoretical research and the technology of metal particle processing in the micro-nano scale is more and more mature. The properties of surface isobaric elements of different metal nanostructures have become a very hot research topic. This research has also formed a rapidly developing new subject. Based on the current research status of surface isophosphonic photonics, most of the current studies are focused on complex two-dimensional nanostructures. In this paper, a method of producing complex surface isopultionic properties by coupling simple geometric structures is proposed. This paper is mainly divided into three parts. In the first part, some numerical calculation methods and the software used in this paper are introduced. In the second part, some basic nanostructures and surface isopherons of nano-dimer are introduced. In the third part, the box-square disk is designed. SRD) composite structure has studied the optical properties of surface isoexcitators and focused on some high order surface resonance characteristics due to the breaking of symmetry. The contents of each part are described as follows; In the first part, some commonly used numerical calculation methods are introduced, and the numerical calculation software used in this paper is briefly introduced, in which the FDTD method is mainly introduced. Discrete dipole approximation (DDA) method. And finite element FEMM). Three common numerical simulation algorithms are presented in this paper. Then, the COMSOL using finite element method in this paper is introduced emphatically. Multiphysics software. For which modeling needs to pay attention to some of the settings such as boundary conditions. The setting of the port and the calculation of the S parameters, the initial value and the setting of the background field are all explained in detail. The second part: we study the properties of the surface isopotons of some relatively basic structures from the simplest nanospheres. After that, some properties of surface isophosphorus of nano-particle dimer are introduced. A method of generating dark isoexciton resonance mode in dimer is introduced. Part 3: a frame / disk SRD structure is designed. By changing the relative position of the square disk and the square frame of the SRD structure, different degrees of asymmetry can be obtained, thus adjusting the surface isoexciton resonance mode of the square frame. A higher order vibration mode is produced or some resonance order that cannot be excited under a symmetric structure is complemented.
【学位授予单位】：陕西师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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