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1、基于石墨烯的宽带可调谐超材料吸收器的研究目 录中文摘要IABSTRACTII第一章 绪论11.1 超材料吸收器的概念及研究意义11.2 传统超材料吸收器的研究进展11.3 频率可调谐超材料吸收器的研究进展51.3.1 基于二极管的可调谐超材料吸收器51.3.2 基于光敏材料的可调谐超材料吸收器61.3.3 基于相变材料的可调谐超材料吸收器71.3.4 基于石墨烯材料的可调谐超材料吸收器81.4 论文的主要内容9第二章 基于石墨烯的太赫兹可调谐宽带超材料吸收器112.1 石墨烯特性以及理论模型112.2 吸收器结构设计以及仿真设置122.3 可调谐的吸收特性132.4 可调谐的吸收机理152.4
2、.1 电场分布分析152.4.2 电流分布分析162.5 结构参数以及入射角度对吸收特性的影响172.6 本章小结19第三章 全石墨烯-介质的太赫兹波段超材料吸收/反射器203.1 全石墨烯-介质吸收器的结构模型213.2 吸收/反射特性分析223.3 吸收器的阻抗特性分析243.4 不同状态下电场/表面电流分布分析263.5 石墨烯参数以及介质厚度对吸收特性的影响分析283.6 不同入射角以及偏振角的变化吸收特性的影响分析303.7 本结果与其他文献结果对比313.8 本章小结31第四章 总结与展望334.1 全文总结：334.2 未来展望：33参考文献36攻读学位期间取得的研究成果42致谢
3、43个人简况及联系方式43承诺书44学位论文使用授权声明45中 文 摘 要超材料是一种自然界不存在的人造材料，具有许多自然材料不具有的独特性质。超材料吸收器作为超材料研究的一个重要分支，是当前研究的一个热点。传统的超材料通常为金属谐振器-介质-金属底板构成“三明治”结构，在特定的频段内可实现对电磁波的完美吸收。近年来，可调谐超材料吸收器由于在不改变其结构参数的情况下，可改变其吸收频段，在传感、检测、能量收集等方面具有广泛的应用前景。通常，实现频率调谐的方法包括可开关二极管、相变材料、光敏材料以及石墨烯等。本文主要基于石墨烯材料，设计了两种太赫兹宽带超材料吸收器，采用CST商业软件进行仿真分析，
4、研究了所设计吸收器的吸收特性与吸收机理。主要内容如下：第一章设计了一种基于未图案化石墨烯叠加金属谐振器的可调谐超材料吸收器。该吸收器工作太赫兹频段，其单元结构由“米”字型缝隙金属谐振器、无图案化的石墨烯层、介质层和金属底板四层构成，通过调节单层无图案石墨烯的费米能，实现对吸收频率动态可调谐的目的，同时满足宽带吸收特性。仿真研究表明，当费米能调控为0.1eV时，吸收率达90%以上的绝对带宽为1.25THz，相对带宽达到49%，当费米能调控为0.5eV时吸收频段蓝移，高于90%吸收率的带宽仍可达1.12THz。通过对电磁场的分析，探究了吸收机理。研究了结构设置参数以及电磁波入射角发生改变时，提出的
5、吸收器吸收特性的影响情况。第三章在第二章的基础上，通过对石墨烯层图案化，设计了一种实现吸收带宽以及吸收强度均可调谐的超材料吸收/反射器。通过独立调控图案化石墨烯层上的石墨烯方片和石墨烯方环的费米能，达到调节该吸收器的吸收强度和吸收带宽的目的。当顶层石墨烯方片与放环均不施加偏置电压时，该结构可以实现对入射的电磁波完全反射，其工作状态为反射状态。当石墨烯方片和两个石墨烯方环的费米能均为1eV时，该结构工作在宽带吸收状态，其吸收超过90%的吸收带宽范围为2.0THz到3.75THz，相对吸收带宽达到61%。通过研究其阻抗特性和电场分布很好地解释了宽带吸收的机制；分析了不同参数以及偏振角与入射角对吸收
6、器的影响，发现该结构具有入射电磁波偏振角、入射角均不敏感的宽带吸收特性。第四章总结全文的研究成果，展望未来超材料吸收器的工作进展。关键词：太赫兹；石墨烯；可调谐；吸收器ABSTRACTMetamaterial is a man-made material that doesnt exist in nature. When its in nature, the materials refractive index is usually positive, but in metamaterials, its refractive index is negative. This has attrac
7、ted widespread attention from researchers. Material absorbers as a branch of metamaterials have also been extensively studied. The traditional metamaterial absorber structure is usually made up by a sandwich structure: a metal base plat, a dielectric, a metal resonator structure. When the structer i
8、s fixed, it can achieve perfect absorption of electromagnetic waves in a specific frequency band. In recent years, various of metamaterials absorbers have been proposed by scholars. Among them, tunable metamaterial absorbers have been widely studied because they can achieve absorption effects at dif
9、ferent frequencies. These absorbers are used in the fields of sensing, detection, reflectors, etc. due to their perfect absorption effect.Methods to achieve frequency tunability include switchable diodes, phase change materials, photosensitive materials, graphene, and more. This article mainly studi
10、es tunable metamaterial absorbers based on graphene materials: a frequency-tunable metamaterial hand wash based on unpatterned graphene; an absorption bandwidth and intensity-tunable absorption / reflector. CST commercial software was used for simulation analysis, and the absorption characteristics
11、and absorption mechanism of the proposed absorber were studied.In chapter 1, mainly introduces the research background of metamaterial absorbers, implementation methods and research progress.In chapter 2, based on known theoretical methods, a tunable metamaterial absorber based on unpatterned graphe
12、ne was designed. The absorber works in the terahertz frequency band, and its unit structure consists of a m-shaped slot metal resonator, an unpatterned graphene layer, a dielectric layer and a metal base plate. By adjusting the bias voltage applied to the graphene can achieve tunable broadband absor
13、ption characteristics. Simulation studies show that the absolute bandwidth is more than 90% when the Fermi energy is 0.1eV, and the absolute bandwidth is 1.25THz, and the relative bandwidth is 49%. When the Fermi energy is 0.5eV, the blue band of the absorption band is higher than The bandwidth can
14、still reach 1.12THz. By analyzing the electromagnetic field, the absorption mechanism was explored. The influence of the parameters and the incident angle on the absorption characteristics of the absorber was studied.In chapter 3, Based on the second chapter, by patterning the graphene layer, a meta
15、material absorber/reflector with adjustable absorption bandwidth and absorption intensity is designed. By independently adjusting the Fermi energy of the graphene square sheet and the two graphene square rings, the absorption intensity and frequency of the absorber can be adjusted. When no voltage is applied to the top graphene pattern layer, the structure works in a reflective state. When the Fermi energy of the graphene square sheet and the two graphene square rings are both 1eV, the structure works in a broadband absorption state, and the bandwidth range of which the absorpt
