金属纳米缝产生的表面等离激元光学格子及其相位涡旋研究

发布时间：2018-01-28 04:53

本文关键词： 表面等离激元光学格子干涉涡旋　出处：《山东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：表面等离激元(SPPs)是指被局域在金属/介质表面的沿着金属表面传播的电子疏密波,是由金属表面自由振动的电子和光子相互作用耦合而成的混合激发态。表面等离激元是一种倏逝波,其独特的性质引起了人们在表面等离激元聚焦、涡旋以及光场调控等方面广泛的研究兴趣。尤其是近年来,关于表面等离激元光场操控方面的研究很热,现在对于用纳米缝、孔等结构产生一些简单的光场图样和涡旋的研究已经发展的较为成熟了。但由于金属纳米缝激发表面等离激元在激发效率和探测光场方法方面的限制,以及现有理论的局限性,对于设计产生一些特定的光场图样和高阶相位涡旋仍然存在难度,需要进一步深入地展开研究。在本论文中,我们通过利用惠更斯-菲涅耳原理和散射成像法,以及时域有限差分法(FDTD solutions)等计算机工具软件开展了对金属纳米缝产生表面等离激元光学格子及其相位涡旋做了研究。我们设计了沿螺旋线排列的具有不同段数的弧缝样品,在理论上我们根据已有的金属缝结构激发表面等离激元光场参数并结合惠更斯-菲涅耳原理,推导出了样品缝激发的表面等离激元场的表达式,并以此为理论基础计算得出了样品产生的光场图样。实验上我们搭建了马赫-增德尔干涉系统用散射显微成像法收集样品激发的表面等离激元场并用SCOMS记录形成的光场图样,产生的散射表面等离激元场与参考光相干涉,通过傅里叶变换的方法从得到的干涉条纹中提取出光场信息,得到了不同的光学格子图样,并且我们通过构建样品状结构的衍射模型,分析了格子产生的机理。我们设计了不同拓扑荷值的样品,利用入射光和金属纳米缝的相互作用,通过FDTD solutions计算产生了高阶涡旋格子。本论文的主要内容由以下五部分组成。第一部分是绪论,我们介绍了表面等离激元的研究背景;并讨论了表面等离激元的理论波方程;得出了表面等离激元的几个特征参量及其表达式和色散曲线关系;介绍了表面等离激元实验上的激发方式及其实验上常用的几种探测方法;介绍了表面等离激元的一些应用和研究现状;最后介绍了本文的研究目的和研究内容。第二部分,我们利用惠更斯-菲涅耳原理结合金属缝激发表面等离激元的特性推导出了由n段弧缝组成的样品激发表面等离激元光场的表达式;并设计了不同缝数和排布的结构,根据得出的理论公式对每个结构所产生的光场图样进行了理论计算;通过所得计算结果可以看出,在每个样品得到的光强图样的中心区域分别产生了由六个光强亮斑沿圆环分布的Honeycomb格子、由六个椭圆状光强亮斑构成的著名的Kagome格子、由五个呈圆形分布的光强亮斑组成的五花瓣状格子和由七个呈圆形分布的光强亮斑组成的七花瓣状格子。第三部分我们通过在金膜上设计并刻蚀由6段、5段和7段纳米弧缝组成的结构,在线偏振光入射样品下,获得了表面等离激元场中微米级表面等离激元光学格子。实验上,我们通过搭建了马赫-增德尔干涉系统并利用全息理论提取出了实验所得表面等离激元场光场信息,我们得到在样品形成的强度图样。通过对所得结果的光强图和第二章中理论计算所得光强图样进行对比,发现实验结果与计算结果高度一致。我们对各个样品所形成的光学格子进行了测量,发现格子的尺寸在微米量级。为了更清楚地理解格子产生的机理,我们利用传统的6针孔屏作类比探究了格子的产生机制。第四部分设计了沿不同开口大小的螺旋线分布的具有不同段数不同排布的弧缝结构样品;在左旋/右旋圆偏振光从基底侧照射样品时,得到了具有任意高阶涡旋的表面等离激元光学格子;我们用时域有限差分(FDTD solutions)软件进行了数值计算,得到了从一到五阶拓扑荷结构的涡旋和对应的不同格子光强图样,例如Kagome格子、Honycomb格子,五花瓣和七花瓣状格子等。第五部分,总结了本学位论文所研究的内容和创新点,并对下一步将要进行的工作做了简单介绍。
[Abstract]:The surface plasmon (SPPs) is localized on the metal / dielectric surface along the electron density wave propagation in metal surface, is a mixture of excited state by vibration on the surface of metal free electron and photon interaction coupling together. Surface plasmon is an evanescent wave, due to its unique properties the people in the surface plasmon focusing, widely interested in the study of vortex and the light field regulation. Especially in recent years, research on surface plasmon polariton manipulation of the light field is very hot, now for the nano slit, some simple light field pattern and vortex research has been the development of more mature pore structure. But because the metallic slit excitation limit in surface plasmon excitation efficiency and probe light field method, and the limitations of existing theories, to design some specific patterns of light field and higher order phase vortex is still However, the difficulty, need further research. In this thesis, we use Huygens Fresnel principle and scattering imaging method, and the finite difference time domain method (FDTD solutions) and other computer software tools to carry out surface plasmon optical lattice and phase vortices are researched for metallic slit. We the design of the distributed along a helical line with different number of arc seam samples, we theoretically according to the existing metal slit structure excited surface plasmon optical parameters and combining the Huygens Fresnel principle is derived from the surface of sample joints stimulate expression of polaritons field, light field pattern sample the calculated based on experiment. We set up Maher by Del interferometer with scattering microscopic imaging method to collect samples excited by surface plasmon field and SCOMS record Light field pattern formation, the scattering of surface plasmon field and reference light interference, to extract information from the optical field to obtain the interference fringes by Fourier transform method, the optical lattice pattern is different, and we construct the diffraction model sample structure, analyzes the mechanism of the lattice we designed the different topologies of the sample, using the interaction between incident light and metallic slit, through the FDTD solutions calculation of high-order vortex lattices. The main content of this paper consists of five parts. The first part is the introduction, we introduce the research background of surface plasmon polaritons are discussed; the surface plasmon polariton wave equation theory; the surface plasmon of several characteristic parameters and their expressions and dispersion relations polaritons; introduces the surface plasmon polariton mode excitation experiment and its experience Detection of several commonly used methods are introduced; some plasmonic applications and research status of the surface; and finally introduces the research purpose and research content. The second part, we use the Huygens Fresnel principle combined with metal joints excited surface plasmon polaritons characteristics derived out by N arc seam sample surface excitation the expression of excitation light field; and the design of the structure of different slot number and arrangement, according to the theory of light field pattern formula is generated for each structure is calculated by the calculation results; it can be seen that in the central region of light intensity pattern each sample was obtained respectively by six light intensity the bright spots along the ring distribution of Honeycomb lattice, consisting of six oval shaped light spots of the famous Kagome lattice, is composed of five Wuhua flap lattice circular distribution of the spot intensity and composition by seven A seven petal shaped lattice light circular distribution bright spot composition. In the third part, through the design and etching on Au film by 6, 5 and 7 segments of arc seam nano structures composed of linearly polarized light incident sample, the surface plasmon of micron element field surface plasmon optics lattice. In experiment, we set up by Maher by Del interferometer system and using holographic theory to extract the surface plasmon field information, we get the intensity pattern in the formation of the sample. Based on the theory results of intensity distribution and the second chapter is the light intensity pattern comparison, found the experimental results and the calculation results are highly consistent. We formed optical lattice of each sample were measured and found the size of grid at the micron scale. In order to better understand the mechanism of grid generation, we use the traditional 6 pin The screen hole analogy explores the mechanism. The fourth part of the design of the lattice distribution along the helix with different opening sizes with different number of segments of the different arrangement of the arc seam structure of samples; in the left / right circularly polarized light from the substrate side when the sample is irradiated with the arbitrary high order vortex surface plasmon optical lattice; we use the finite difference time domain (FDTD solutions) software is used to carry out numerical calculation, obtained from a scroll to five order topological structure and corresponding lattice light intensity pattern, such as the Kagome lattice and Honycomb lattice, five petals and seven petal shaped lattice. The fifth part summarizes the thesis research the content and innovation, and the next step will be to do the work of a simple introduction.

【学位授予单位】：山东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG111

【参考文献】