石墨烯表面等离子体波以及在太赫兹调制器中的应用研究

发布时间：2018-05-28 21:20

本文选题：石墨烯 + 表面等离子体波　；参考：《中国计量学院》2015年硕士论文

【摘要】：石墨烯材料具有稳定、高强度、高电导率等优良的物理特性,而且拥有零带隙的能带结构,因此可通过改变载流子浓度达到调节石墨烯电导率的目的。在一定条件下石墨烯可以支持表面等离子体波的传输,并可通过外加偏置电场来控制表面等离子体波的相关特性,这和传统不可调的金属材料相比是一巨大优势。基于以上出众的特性,石墨烯成为设计可调器件的理想材料。本文研究了石墨烯表面等离子体波的色散特性,着重研究通过电场偏置对石墨烯表面波的调节作用。基于Maxwell方程组和石墨烯的边界条件,对表面波进行理论分析。通过理论推导得到TE、TM模式表面波存在的条件,并运用色散方程计算两种模式下表面波的约束特性和传输衰减。计算结果表明在石墨烯-二氧化硅-硅模型结构上存在的TM表面波,在THz及红外频段内具有较小的传输损耗,且具有良好的约束性即能将能量紧密的约束在石墨烯表面附近。以石墨烯等离子体波波导结构为出发点,并结合石墨烯表面等离子体波的传输及电可调特性,设计基于石墨烯表面等离子体波波导结构的太赫兹调制器。首先设计了由单条石墨烯带所构成的调制器,本调制器通过不同的偏置电压来获得不同的传输衰减,从而达到调制的目的。该调制器具有28%的调制深度,并利用等效电路的方法计算得到该调制器的RC时延参数进而获得调制速率,该调制器3d B的调制带宽可以达到45MHz。由于单条带结构调制器的调制深度并不理想,之后设计了由三条石墨烯带所构成的耦合结构调制器,通过对耦合臂石墨烯带添加调制信号,来改变表面等离子体波的耦合效率和传输衰减,从而得到调制特性。采用耦合结构之后对调制器的调制深度有非常大的提升,耦合结构的调制器可以达到76%的调制深度,并具有40MHz的调制带宽。
[Abstract]:Graphene materials have excellent physical properties such as stable, high strength and high conductivity, and have the energy band structure with zero band gap. Therefore, the conductivity of graphene can be adjusted by changing carrier concentration. Graphene can support surface plasma wave transmission under certain conditions and can control the characteristics of surface plasma wave by applying bias electric field. This is a great advantage over traditional unadjustable metal materials. Based on the above outstanding characteristics, graphene is an ideal material for the design of adjustable devices. In this paper, the dispersion characteristics of graphene surface plasma waves are studied, and the adjustment of graphene surface waves by electric field bias is emphasized. Based on the Maxwell equations and the boundary conditions of graphene, the surface wave is theoretically analyzed. The conditions for the existence of surface waves in Te-TM mode are obtained by theoretical derivation, and the constraint characteristics and propagation attenuation of surface waves in two modes are calculated by using dispersion equation. The results show that the TM surface wave in the graphene silica silicon model has a small transmission loss in the THz and infrared band, and has good constraint, that is, the energy can be tightly confined near the surface of graphene. A terahertz modulator based on graphene surface plasma wave waveguide structure is designed based on graphene plasma wave waveguide structure, combined with the transmission and electrically adjustable characteristics of graphene surface plasma wave. A modulator composed of a single graphene band is designed. The modulator obtains different transmission attenuation through different bias voltages, so as to achieve the purpose of modulation. The modulation depth of the modulator is 28%, and the RC delay parameter of the modulator is calculated by the equivalent circuit method, and the modulation rate is obtained. The modulation bandwidth of the modulator 3dB can reach 45MHz. Because the modulation depth of the single band structure modulator is not ideal, a coupled-structure modulator composed of three graphene bands is designed. The modulation signal is added to the graphene band of the coupling arm. In order to change the coupling efficiency and propagation attenuation of the surface plasma wave, the modulation characteristics are obtained. The modulation depth of the modulator is greatly improved with the coupling structure. The modulation depth of the modulator with the coupling structure can reach 76% and the modulation bandwidth of the 40MHz can be obtained.
【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;TN761

【相似文献】