光学天线调控的光辐射研究

发布时间：2018-05-15 23:08

本文选题：光学天线 + 表面等离激元　；参考：《中国科学技术大学》2016年博士论文

【摘要】：基于光学天线调控的光辐射及其应用是微纳光学研究的热点之一。光学天线可以对光场进行高效地耦合与高度地局域化,是一种实现自由空间传播光场和局域光场之间高效转换的纳米结构,是连接两者之间的桥梁。由于光学天线具有很高的局域场增强和很好的方向性等特点,利用光学天线可以实现局域量子点发光的高效定向辐射。因此光学天线在电磁能量耦合、转化以及相干控制的过程中可以起到至关重要的调控与放大作用,在超灵敏单分子探测、局域激射(单光子源)、纳光电子集成芯片、量子调控等方面都具有很重要的应用。本论文围绕光学天线调控增强发光的基本物理过程,研究了光学天线调控的自发辐射增强效应、辐射效率、方向性,以及光学天线结构中的磁模式、非局域效应对其辐射调控的影响。本论文的主要研究工作如下：1.基于多球并矢格林函数的解析算法,分析了偶极子光源与金属-介质复合光学天线的相互作用过程。引入辐射增强因子来综合考察光学天线调控的自发辐射增强与辐射效率。进而设计了由银纳米球与介质纳米球组成的金属-介质复合光学天线,实现了宽谱的高Purcell因子与高效辐射。2.研究了贴片光学天线结构中的模式特性及其光辐射调控。构造了银纳米球与双曲超材料多层膜耦合的贴片光学天线。通过调节银纳米球的大小以及多层膜中银膜与硅膜的厚度比例,增强了双曲超材料中体模式的激发。引入磁模式来增加光学天线对光辐射的调控途径,设计了支持多种间隔层模式(gap mode)的银纳米长方体贴片光学天线,利用非对称电偶极子激发该光学天线的电模式与磁模式共振耦合,实现了贴片光学天线调控的单向辐射。3.基于局域近似模型,以银纳米长方体组成的二聚体光学天线为例,研究了间隔层中的非局域效应。分析了在电偶极子与磁偶极子的不同激发方式下,不同间隔层参数(厚度、折射率)下非局域效应对光学天线调控的辐射特性的影响。讨论了非局域效应引入后,光学天线对自发辐射增强调控的强度与共振谱的变化。本论文的创新点和特色：1.通过引入金属-介质复合光学天线结构,以解决金属结构光学天线损耗高,介质结构光学天线自发辐射增强低的矛盾问题,设计优化金属-介质复合光学天线的结构参数,实现了宽谱的高效率高增强辐射。2.引入磁模式,设计了银纳米长方体贴片光学天线。采用非对称的激发方式,通过调节银纳米长方体的尺寸结构,使得电模式与磁模式共振耦合,实现了面内的单向辐射。3.在具有极小间隔层的光学天线结构中,引入非局域效应的影响。研究了电偶极子和磁偶极子激发下,间隔层中的非局域效应。对比分析了不同间隔层参数(厚度、折射率)下非局域效应对光学天线调控的辐射特性的影响。
[Abstract]:Optical radiation based on optical antenna regulation and its application is one of the hotspots in micro-nano optics research. Optical antenna can efficiently couple and localize the light field. It is a kind of nanostructure which can realize the efficient conversion between the free space propagation light field and the local light field. It is a bridge connecting the two fields. Because the optical antenna has the characteristics of high local field enhancement and good directivity, the high efficiency directional radiation of local quantum dot luminescence can be realized by using the optical antenna. Therefore, the optical antenna can play an important role in controlling and amplifying the electromagnetic energy coupling, conversion and coherence control, in the hypersensitive monolayer detection, local excitation (single photon source, nanoptoelectronic integrated chip), the optical antenna can play an important role in the process of electromagnetic energy coupling, conversion and coherence control. Quantum regulation and other aspects have very important applications. This paper focuses on the basic physical process of optical antenna regulation enhancement luminescence, studies the spontaneous emission enhancement effect, radiation efficiency, directivity and magnetic mode in the optical antenna structure. Effects of nonlocal effects on radiation regulation. The main research work of this thesis is as follows: 1. Based on the analytical algorithm of multi-sphere dyadic Green's function, the interaction process between dipole light source and metal-dielectric composite optical antenna is analyzed. Radiation enhancement factor is introduced to investigate the spontaneous emission enhancement and radiation efficiency of optical antenna. Furthermore, the metal-dielectric composite optical antenna composed of silver nanospheres and dielectric nanospheres is designed. The high Purcell factor and high efficiency radiation of wide spectrum are realized. The mode characteristics and optical radiation regulation in the structure of patch optical antenna are studied. A patch optical antenna coupled with hyperbolic supermaterial multilayer film was constructed. By adjusting the size of silver nanospheres and the thickness ratio of silver film to silicon film in the multilayer film, the excitation of bulk mode in hyperbolic supermaterial was enhanced. The magnetic mode is introduced to increase the optical radiation regulation of optical antenna. A silver nano-cuboid patch optical antenna supporting multiple spacer modes is designed. An asymmetric electric dipole is used to excite the resonant coupling between the electric mode and the magnetic mode of the optical antenna, and the unidirectional radiation of the patch optical antenna is realized. Based on the local approximation model, the nonlocal effect in the spacer is studied by taking the dimer optical antenna composed of silver nanocrystalline cuboids as an example. The influence of nonlocal effects on the radiation characteristics of optical antenna controlled by different spacer parameters (thickness and refractive index) under different excitation modes of electric dipole and magnetic dipole is analyzed. The change of intensity and resonance spectrum of the enhancement of spontaneous emission by optical antenna after the introduction of nonlocal effect is discussed. The innovation and characteristic of this thesis: 1. The structure of metal-dielectric composite optical antenna is introduced to solve the problems of high loss of metal structure optical antenna and low spontaneous emission enhancement of dielectric structure optical antenna. The structural parameters of metal-dielectric composite optical antenna are designed and optimized. A wide spectrum of high efficiency and high enhancement radiation. 2. A silver nano cuboid patch optical antenna is designed by introducing magnetic mode. By adjusting the size structure of silver nanocrystalline cuboids by asymmetric excitation mode, the resonant coupling of electric mode and magnetic mode is realized, and the in-plane unidirectional radiation. 3 is realized. The influence of nonlocal effect is introduced in the structure of optical antenna with minimal spacer. The nonlocal effects in the spacer excited by electric dipole and magnetic dipole are studied. The effects of nonlocal effects on the radiation characteristics of optical antennas under different spacer parameters (thickness and refractive index) are compared and analyzed.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN820

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