基于石墨烯的光子晶体特性及其应用研究

发布时间：2018-04-05 01:19

本文选题：石墨烯　切入点：光子晶体　出处：《北京邮电大学》2017年硕士论文

【摘要】：2004年,安德烈和康斯坦丁第一次成功地从石墨中分离出石墨烯,证实它可以单独存在,并获得了诺贝尔奖。石墨烯在室温下具有极高的电子迁移率,其电导率具有电压、温度等可调特性,在可调太赫兹功能器件方面有重要应用。论文研究了一维石墨烯光子晶体的色散特性和缺陷模特性,并基于石墨烯设计了两种类型可调宽带极化不敏感太赫兹吸波器。论文主要工作如下:(1)基于Maxwell方程推导了一维各向异性石墨烯光子晶体的传输矩阵方程,并由此得到了复数色散关系,分析了其传输特性和衰减特性。研究发现,由于石墨烯的介电常数为复数特性,其对应的色散可分为两部分,一种是对应于波矢实部的传输曲线,一种是对应于波矢量虚部的损耗特性。最后采用仿真软件建立模型,进一步验证了理论推导的正确性。(2)提出在一维石墨烯光子晶体中引入两层和三层缺陷,发现由于多层缺陷的引入,在原带隙范围出现了多个缺陷模,并且缺陷模频率和幅度具有外部电压可调性。进一步研究发现缺陷模的频率、幅度和个数受缺陷层个数、层数以及缺陷材料的影响。当双层缺陷周期数增多时,缺陷模幅度减小。改变缺陷层中间光子晶体的周期数,缺陷模的峰值没有明显变化,但缺陷模的位置随着周期数的增加向带隙的中心移动。当缺陷层中间的光子晶体周期数增大到一个阈值时,双缺陷模合成一个。当缺陷层位置从对称变成不规则时,缺陷模峰值增大。(3)基于石墨烯的吸波结构大多为窄带,并且往往是极化敏感的。论文基于石墨烯材料设计了两种类型的宽带极化不敏感可调太赫兹吸波器,利用模式叠加原理和阻抗匹配原理分析了宽带吸波器的物理机理,探讨了其在宽带可调太赫兹吸波方面的重要应用。最后讨论了石墨烯电导率的表达方式对石墨烯吸波器吸收特性的影响。基于石墨烯的光子晶体在太赫兹可调功能器件方面有重要应用,本论文的研究将进一步推动太赫兹可调多频段窄带滤波器和极化不敏感宽带吸波器的发展和应用。
[Abstract]:In 2004, Andrea and Constantine successfully isolated graphene from graphite for the first time, proving that it could exist alone and winning a Nobel Prize.Graphene has a very high electron mobility at room temperature, and its conductivity has adjustable characteristics such as voltage, temperature, etc. It has important applications in tunable terahertz functional devices.In this paper, the dispersion characteristics and defect modes of one-dimensional graphene photonic crystals are studied, and two types of tunable wideband polarization insensitive terahertz absorbers are designed based on graphene.The main work of this paper is as follows: (1) based on the Maxwell equation, the transfer matrix equation of one-dimensional anisotropic graphene photonic crystal is derived, and the complex dispersion relation is obtained, and the propagation and attenuation characteristics are analyzed.It is found that because the dielectric constant of graphene is complex, its dispersion can be divided into two parts, one is the transmission curve corresponding to Yu Bo's vector real part, the other is the loss characteristic corresponding to the imaginary part of Yu Bo vector.Finally, the simulation software is used to establish the model, which further verifies the correctness of the theoretical derivation. (2) A two-layer and three-layer defect is introduced into the one-dimensional graphene photonic crystal, and it is found that the multi-layer defect is introduced.There are several defect modes in the original band gap range, and the frequency and amplitude of the defect mode are adjustable by external voltage.It is found that the frequency, amplitude and number of defect modes are affected by the number of defect layers, the number of layers and the defect materials.When the number of double layer defect cycles increases, the amplitude of defect mode decreases.The peak value of the defect mode does not change obviously when the period number of the intermediate photonic crystal in the defect layer is changed, but the position of the defect mode moves to the center of the band gap with the increase of the period number.When the number of photonic crystal cycles in the middle of the defect layer increases to a threshold, a double defect mode is synthesized.When the position of defect layer changes from symmetry to irregularity, the peak value of defect mode increases. 3) the absorption structure based on graphene is mostly narrow-band and is often polarization-sensitive.In this paper, two types of wideband polarization insensitive tunable terahertz absorbers are designed based on graphene materials. The physical mechanism of wideband absorbers is analyzed by mode superposition principle and impedance matching principle.Its important application in wideband tunable terahertz wave absorption is discussed.Finally, the influence of the expression of graphene conductivity on the absorption characteristics of graphene absorber is discussed.Photonic crystals based on graphene have important applications in terahertz tunable devices. The research in this paper will further promote the development and application of terahertz tunable multi-band narrowband filters and polarization-insensitive broadband absorbers.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11

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