非线性可调谐表面等离激元器件的研究

发布时间：2019-05-30 09:39

【摘要】：表面等离激元可以实现将电磁波束缚在亚波长尺度,打破了光固有的衍射极限,使得在纳米尺度操控光波成为可能,并且在多种学科中有着前所未有的重要的应用,这一研究领域被统称为Plasmonics。在贵金属比如金和银以及一些新兴的材料比如石墨烯中支持具有较低损耗的表面等离激元。实现可调谐表面等离激元器件是近些年来表面等离激元研究领域的一个热点。表面等离激元现象会使在金属附近的电磁场得到显著的增强,从而可以让一些光学非线性效应在较低的功率下实现。本文主要针对表面等离激元在几种不同结构中的导波、非线性效应以及可调谐表面等离激元器件的应用进行了一系列深入的理论和仿真研究。本论文取得的主要研究成果与创新点如下:1.提出了一种基于石墨烯包覆介质纳米线表面等离波波导,其无边缘结构的特点可以避免类似于石墨烯纳米带的不规则边缘带来的散射损耗,实现低损耗的传输石墨烯表面等离波。建立了石墨烯包覆纳米线中表面等离波模式的解析模型,深入研究了石墨烯包覆纳米线的各项参数对色散特性的影响。利用一种半解析方法提出了高阶表面等离波模式的截止条件。2.提出并研究了石墨烯包覆纳米线对中的二次谐波产生。通过非共轭洛伦兹互易性定理建立了用于描述二次谐波产生过程的非线性耦合模方程。详细分析了石墨烯包覆纳米线对中的表面等离波模式特性,利用模式相位匹配的方法实现了高效的二次谐波产生,而且相位匹配条件可以通过控制石墨烯包覆纳米线对的间距在不同频率处实现。3.提出并研究了在一对单模石墨烯包覆纳米线中的非线性定向耦合的效应。通过非共轭洛伦兹互易性定理建立了用于描述非线性耦合过程的非线性耦合模方程。在单模石墨烯包覆纳米线对中的耦合行为可以通过输入光功率来控制。4.提出并研究了一种基于石墨烯Split-Ring谐振腔的可调谐表面等离波滤波器。石墨烯Split-Ring谐振腔中支持两种具有相反对称性的谐振模式而且两者对于Split-Ring结构的开口方向有不同的敏感性。该滤波器的滤波特性可以通过调节石墨烯Split-Ring谐振腔的多种参数来灵活控制。5.提出并研究了一种基于金-空气-金结构的缝隙Plasmonic波导的可调谐滤波器。通过在单模缝隙Plasmonic波导中引入周期性缺陷形成布拉格光栅结构。利用表面等离波模式对空气缝隙大小的敏感性,通过在两层金属之间施加可变静电场,使得金层在库仑力的作用下产生形变来调谐空气缝隙的大小,从而改变满足布拉格条件的谐振波长,实现一种可调谐表面等离波滤波器。6.提出并研究了一种在金-空气-金波导结构中基于多模干涉效应2x2光开关。利用多模区所支持的两个具有相反对称性的模式的模式折射率对空气缝隙改变的不同的敏感性,通过控制多模缝隙Plasmonic波导中空气缝隙的大小改变输出端两个模式之间的相位差,实现输出端在直通、交叉两种状态间的切换,实现了一种2x2光开关。
[Abstract]:Surface plasmon polaritons can be used to bind the electromagnetic wave to the sub-wavelength scale, and the inherent diffraction limit of the light is broken, so that the light wave can be controlled at the nanometer scale and has an unprecedented important application in a variety of disciplines, and the field of research is generally referred to as Plasmonics. High-loss surface plasmon is supported in precious metals such as gold and silver and some emerging materials, such as graphene. It is a hotspot in the field of surface plasmon research in recent years. The surface plasmon phenomenon will result in a significant enhancement of the electromagnetic field near the metal, so that some optical non-linear effects can be achieved at lower power. In this paper, a series of in-depth theoretical and simulation studies have been carried out on the application of surface plasmon in several different structures, such as guided wave, non-linear effect and tunable surface. The main research results and innovation points of this thesis are as follows:1. The invention provides a graphene-coated medium nanowire surface and the like off-wave guide, which has the characteristics of no edge structure, and can avoid scattering loss caused by the irregular edge of the graphene nanobelt and realize the low-loss transmission graphene surface and the like off-wave. The analytical model of the off-wave pattern of the surface of the graphene-coated nano-wire is established, and the influence of the parameters of the graphene-coated nano-wire on the dispersion property is studied. By means of a semi-analytical method, the cut-off condition of the high-order surface and other off-wave modes is presented. The second harmonic generation of graphene-coated nanowire pairs is proposed and studied. The non-common lorentz reciprocity theorem is used to establish a nonlinear coupled mode equation for describing the second harmonic generation process. In this paper, the off-wave mode characteristics of the surface of the graphene-coated nanowire pair are analyzed in detail, and the high-efficiency secondary harmonic generation is realized by the method of the mode phase matching, and the phase matching condition can be realized at different frequencies by controlling the spacing between the graphene-coated nano-wire pairs. The effect of nonlinear directional coupling in a pair of single-mode graphene-coated nanowires is proposed and studied. The nonlinear coupling model equation for describing the nonlinear coupling process is established by the non-common lorentz reciprocity theorem. The coupling behavior in a single-mode graphene-coated nanowire pair can be controlled by the input of optical power. An off-wave filter based on the tunable surface of a graphene-split-Ring resonant cavity is presented and studied. Two resonant modes with opposite symmetry are supported in the graphene Split-Ring resonant cavity, and both have different sensitivity to the opening direction of the Split-Ring structure. The filter characteristics of the filter can be controlled flexibly by adjusting various parameters of the graphene Split-Ring resonant cavity. A tunable filter for the gap Plasmon waveguide based on the gold-air-gold structure is presented and studied. A bragg grating structure is formed by introducing periodic defects in a single-mode slit plasmonic waveguide. by applying a variable electrostatic field between the two layers of metal, the gold layer is deformed to tune the size of the air gap by applying a variable electrostatic field between the two layers of metal, An off-wave filter, such as a tunable surface, is implemented. A multi-mode interference effect 2x2 optical switch in a gold-air-gold waveguide structure is presented and studied. by controlling the phase difference between the two modes of the output end by controlling the size of the air gap in the multimode gap Plasmon waveguide by controlling the difference between the two modes of the output end by controlling the size of the air gap in the multimode gap Plasmon waveguide, The switching between the two states realizes a 2x2 optical switch.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O441;O485

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