人工表面等离子体及其亚波长波导的特性研究

发布时间：2018-01-15 10:25

本文关键词：人工表面等离子体及其亚波长波导的特性研究　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：表面等离体子激元(surface plasmon polaritons,SPPs)是一种可以在金属/介质界面上局域地传播的表面电磁波,存在于紫外、可见光和近红外频段。由于SPPs有望突破衍射极限,为光子器件的小型化和集成化带来了希望,因此受到广泛关注。人工表面等离子体激元(spoof SPPs,SSPPs)是SPPs在太赫兹和微波波段的一个重要拓展,它本质上是一种被金属表面周期性的几何结构(凹槽,孔,金属粒子等)约束着传播的表面电磁波。它的色散关系主要由结构参数控制,在应用中具有很大的灵活性。近年来的研究表明,SSPPs可与太赫兹技术、微波技术、超材料以及光子晶体等领域的知识对接,具有很广阔的应用前景。本文对SSPPs及其亚波长波导的特性进行了理论分析,并设计了具有特殊性能的亚波长器件。具体内容如下:提出和研究L形槽阵列光栅波导。首先利用模式展开法和电磁场的连续性条件推导L形槽阵列光栅波导中的SSPPs的色散关系式,并利用电磁仿真软件进行模拟验证。然后解析讨论SSPPs的色散关系对横向槽深度的敏感性。以此为基础,讨论L槽阵列光栅波导在彩虹捕获效应中的应用。最后,分析具有多个横向槽的组合槽阵列光栅波导,以解决L形槽的横向槽受周期大小限制的问题。研究结果表明,L形槽可以等效为深度更大的矩形槽,给矩形槽添加横向槽等同于增加它的深度。提出和分析非矩形槽阵列光栅波导中的SSPPs的色散关系的解析算法。首先利用模式展开法和电磁场的连续性条件,推导T形槽阵列光栅波导中的SSPPs的色散关系式,解析分析各结构参数对SSPPs性质的影响。然后基于矩形槽和T形槽阵列光栅波导的色散关系式,利用类推法推出多层的组合槽阵列光栅波导的色散关系式。由于槽宽度连续变化的槽可以等效为多层的组合槽,所以我们提出的解析算法对其也是适用的。以梯形槽和斜矩形槽阵列光栅波导为例,展示色散关系的解析求解过程。提出的解析算法表明组合槽可以等效为一个矩形槽,等效槽的深度和宽度由各层矩形槽的深度和宽度决定,解释了为什么凹槽形状会影响SSPPs的色散关系。提出和分析非矩形槽的双光栅阵列波导中耦合模的色散关系的解析算法。双光栅阵列波导是由两个面对面放置的凹槽阵列光栅波导构成的,对称的双光栅阵列波导支持对称模和反对称模两种耦合模,凹槽的形状会影响耦合模的性质。首先,利用模式展开法和电磁场的连续性条件分别推导矩形槽的双光栅阵列波导中对称模和反对称模的色散关系式。然后,利用多层组合槽和矩形槽之间的等效代换关系,得到多层组合槽的双光栅阵列波导中耦合模的色散关系式,并给予模拟验证。最后,将梯形槽看作多层的组合槽,解析讨论梯形槽的双光栅阵列波导中耦合模的性质随结构参数的变化。研究表明,双光栅阵列波导的性质由两方面控制,一是构成其的凹槽阵列光栅波导,二是自身的介质间隙宽度。研究由两个超薄矩形槽阵列光栅波导构成的双光栅阵列波导,提出可以激发对称和反对称的耦合模的系统。采用间接激发的思路,利用两对称或反对称的SSPPs的耦合作用,设计出包括共面波导、模式转换器、耦合器和双光栅阵列波导四部分的激发系统。模拟该激发系统的S参数及电磁场分布,证明该系统激发对称和反对称模的有效性。研究由两个超薄平行四边形槽阵列光栅波导构成的双光栅阵列波导。两个超薄平行四边形槽阵列光栅波导可以构成对称或者非对称的双光栅阵列波导。分别讨论两种双光栅阵列波导的耦合模的色散关系随槽的倾斜度的变化,研究结果表明,非对称的双光栅阵列波导对倾斜度的变化更敏感。在某些倾斜度下,耦合模的群速度出现负值,证明该波导可以支持反向波的传输。当倾斜度取特殊值时,第一布里渊区边界出现偶然简并,简并点受波导参数的影响。借助于微带线和槽线之间的能量转换,实现非对称的双光栅阵列波导中的耦合模的激发和传输。
[Abstract]:Surface plasmon polaritons (surface plasmon, polaritons, SPPs) is a kind of metal / dielectric interface in the local spread of the surface electromagnetic waves exist in the ultraviolet, visible and near-infrared bands. Because the SPPs is expected to break the diffraction limit for the miniaturization of photonic devices and integration brings hope therefore, attracted widespread attention. The artificial surface plasmon (spoof SPPs, SSPPs SPPs) is an important development in the microwave and terahertz band, it is essentially a geometric structure of metal periodic (the groove, hole, metal particle) bound surface electromagnetic wave propagation. The dispersion relation of it mainly controlled by the structural parameters, has great flexibility in application. The recent research shows that SSPPs can be used with terahertz technology, microwave technology, knowledge docking metamaterials and photonic crystals, which has broad application prospects. This paper analyses the theory of SSPPs and its characteristics of sub wavelength waveguide, and the design of sub wavelength devices with special properties. The specific contents are as follows: the introduction and research of L slot array waveguide grating. The dispersion relation of the mode expansion method and electromagnetic field continuity conditions are deduced L slot array waveguide grating in SSPPs, and was simulated using the electromagnetic simulation software. Then analysis and discuss the sensitivity of the SSPPs dispersion relation of transverse groove depth. On this basis, discussed the L grating waveguide slot array in the application effect of the rainbow capture. Finally, analysis is provided with a plurality of transverse slot combination grating waveguide slot array, to solve the transverse groove L groove the cycle size limit. The results show that the L slot can be rectangular slot is equivalent to a greater depth, add to the transverse groove rectangular groove is equal to increase the depth of it. Put forward and analysis Analytical method of dispersion relation of rectangular groove waveguide array grating SSPPs. The continuity condition of first using the mode expansion method and electromagnetic field, the dispersion relation is derived T slot array waveguide grating in SSPPs, analysis the influence of structure parameters on the properties of SSPPs. Then the dispersion relation of rectangular slot and T slot array grating waveguide based on the dispersion relation of multilayered waveguide slot array grating combination launched by analogy. Due to the continuous changes of the width of the groove groove can be equivalent to the combination of slot layers, so we proposed the analytic algorithm is also applicable. By the trapezoidal groove and inclined rectangular slot array waveguide grating as an example to show the dispersion relation the analytical solution process. Analytical algorithm show that the combination of slots can be equivalent to a rectangular groove, the groove depth and width by equivalent depth and width of each layer determines the rectangular groove, explains why It will affect the dispersion relation of SSPPs groove shape. Analytic algorithm is proposed and analyzed the dispersion relation coupling mode of double grating waveguide array non rectangular groove. The double grating waveguide array is composed of two face placed groove waveguide array grating, symmetrical double grating array wave guide support symmetric mode and the antisymmetric mode two kinds of coupled mode, the shape of the grooves will affect the properties of coupled mode. First, a double grating array waveguide mode expansion method using the continuity conditions and electromagnetic field are derived in rectangular groove symmetric mode and the antisymmetric dispersion relation model. Then, using the equivalent substitution relationship between multi-layer groove and rectangular groove, dispersion the relationship between coupling mode double grating array waveguide multilayer slot in, and give the simulation. Finally, the trapezoidal groove groove as a combination of multiple layers, analytical discussion guide double grating array wave trapezoidal grooves The change in properties of coupled mode with the structure parameters. The results show that the properties of the double grating waveguide array is controlled by two aspects, one is the waveguide array grating groove, two medium gap width itself. The double optical grid array waveguide consists of two thin rectangular slot array waveguide grating, this system can excitation of symmetric and anti coupled mode known. By indirect excitation of ideas, using two symmetric or antisymmetric coupling of SSPPs, including the design of coplanar waveguide, mode converter, double coupler and grating array waveguide excitation system. The four part of the simulation of the S parameters and the distribution of electromagnetic field excitation system, proves that the system excitation of symmetric and anti symmetric mode. The effectiveness of the double grating array waveguide consists of two thin parallelogram slot array grating waveguide structure. Two thin parallelogram slot array waveguide grating can be To form a double grating waveguide array is symmetric or asymmetric. Discuss the dispersion relation coupling mode of two kinds of double grating array waveguide changes with groove inclination, the results show that the double grating waveguide array is more sensitive to the change of asymmetric tilt. In some inclination, group velocity coupled mode negative, the waveguide can support backward wave propagation. When the inclination of the special value, the boundary of the first Brillouin zone appeared accidental degenerate, effects of degeneracy by waveguide parameters. With the help of energy conversion between microstrip line and slot line, realize the coupling mode of double grating array waveguide asymmetric in the the excitation and transmission.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN25;O53

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