基于石墨烯超材料的太赫兹波调制理论设计

发布时间：2018-02-23 17:52

本文关键词： 石墨烯太赫兹共振调制深度　出处：《西北大学》2017年硕士论文　论文类型：学位论文

【摘要】：太赫兹(THz)技术作为正在迅速发展的技术之一,目前在高速通信、高灵敏传感、生物成像等领域展现出了良好的应用前景。调制器作为该领域的实际化功能器件是太赫兹技术进步的关键之一。由于太赫兹波段表现出与微波和光波的不同性质,传统的调制器件在该波段的应用受到限制。研究发现,由人工构造,具有周期性的阵列结构,且单元结构远小于电磁波波长的超材料为太赫兹调制技术提供了新的研究思路。然而传统的金属超材料的可调谐性并不能满足实际需求。越来越多的实验和理论证明石墨烯作为一种新型的二维纳米材料,具有优异的光电性能,是可调谐太赫兹功能器件的有效材料之一。石墨烯对太赫兹波的吸收取决于带内电导。目前的石墨烯太赫兹调制器件的性能比较低,主要是由于无共振的Drude载流子行为导致的。因此,结构化石墨烯中的离子体响应,以及石墨烯与超材料的结合有望提高太赫兹调制器件的性能。本文提出了一种基于石墨烯的超材料,将石墨烯设计成开口环单元结构阵列在基底上,单元尺寸远小于太赫兹波长。利用CST商用软件对其进行理论计算。首先研究了该结构对单层石墨烯对正入射TM偏振太赫兹波的调制特点,最终达到85%的调制深度,为了进一步增加调制深度,研究多层石墨烯超材料对其调制的特点,调制深度达到99%。随后研究该单层结构以及多层结构对斜入射TM偏振太赫兹波的调制特点,调制深度分别达到81%和96%。在TE偏振太赫兹波条件下,所产生的共振模式不同于TM偏振。在同一频段,通过调整开口的距离,实现了对TE偏振太赫兹波的两个波段的有效调制。与此同时还研究了多层石墨烯超材料对正、斜入射TE偏振太赫兹波的调制特点。总之,该结构的调制性能非常优异,可以在太赫兹调制器、吸收体、探测器等领域有广泛的应用。
[Abstract]:As one of the rapidly developing technologies, Terahertz (THz) technology is currently in the field of high speed communication and high sensitivity sensing. As a practical functional device in this field, modulator is one of the key technologies of terahertz technology. Because terahertz band has different properties from microwave and light wave, The application of traditional modulation devices in this band is limited. And the metamaterials with cell structure far smaller than the wavelength of electromagnetic wave provide a new research idea for terahertz modulation technology. However, the tunability of traditional metal metamaterials can not meet the actual demand. More and more experiments and theories are carried out. It is proved that graphene is a new two-dimensional nano-material. It is one of the effective materials for tunable terahertz functional devices. The absorption of terahertz waves by graphene depends on the in-band conductance. This is mainly due to the nonresonant Drude carrier behavior. Therefore, the ionic response in structured graphene, And the combination of graphene and metamaterials is expected to improve the performance of terahertz modulators. In this paper, a graphene based supermaterial is proposed, in which graphene is designed as an open ring cell array on the substrate. The unit size is much smaller than the terahertz wavelength. The theoretical calculation is carried out by using the CST commercial software. Firstly, the modulation characteristics of the single-layer graphene to the TM polarization terahertz wave with normal incidence are studied, and the modulation depth of 85% is finally achieved. In order to further increase the modulation depth, the modulation characteristics of multilayer graphene supermaterial are studied, and the modulation depth is up to 99. Then, the modulation characteristics of the single-layer structure and the multilayer structure for the oblique incident TM polarization terahertz wave are studied. The modulation depth is up to 81% and 96 respectively. Under the condition of te polarization terahertz wave, the resonant mode is different from TM polarization. In the same frequency band, by adjusting the distance of the opening, The effective modulation of te polarization THz wave is realized. At the same time, the modulation characteristics of multilayer graphene supermaterial pair with normal and oblique incidence te polarization terahertz wave are studied. In a word, the modulation performance of this structure is very good. It can be widely used in terahertz modulator, absorber, detector and so on.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71;O441.4

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