【作者】 王平；

【导师】 姚建铨； 凌福日；

【作者基本信息】 华中科技大学 ， 物理电子学， 2013， 硕士

【摘要】 本论文讨论了太赫兹波段石墨烯中表面等离子体激元纵波模式的增益特性、横波模式下的传输特性并设计、模拟了基于石墨烯的无源光波导传输结构。本论文在麦克斯韦方程组和物质本构方程基础之上，借助于石墨烯介电函数对石墨烯表面等离子体进行了描述。理论上计算了石墨烯纵波模式表面等离子体激元的色散关系和增益特性曲线，并且讨论了表面等离子体增益特性和载流子浓度、动量驰豫时间的关系。另外，由于外加电场对石墨烯载流子浓度具有调制作用，并且设计、光波导传输结构会涉及的折射率和传播常数问题，本论文计算并分析了石墨烯在太赫兹波段电导率的特性。其中，载流子浓度的变化会改变石墨烯中的化学势，同时会改变表面等离子体的物理参量。计算发现，在不同化学势的情况下石墨烯的电导率特性会随之改变，进而会改变石墨烯的介电函数特性。鉴于表面等离子体激元形成条件，我们通过改变石墨烯中电导率分布可以设计出基于石墨烯表面等离子体激元的传输结构。本论文在最后章节中，首先利用COMSOL多物理场模拟软件中的射频（RF）模块展示了石墨烯表面等离子激元在具有不同电导率区域的传输特性，显示出只有在具有合适的电导率区域的石墨烯才能够支持表面等离子传输。然后，基于上述石墨烯表面等离子体传输特性，通过施加不同的外加电压设计并模拟基于石墨烯表面等离子体激元传输的Y型波导。更多还原

【Abstract】 This thesis concerns about the gain characteristic of the longitudinal wave mode and thetransmission prope rty of the transverse wave mode of the surface plasmon in graphene inTHz range. Graphene-based passive waveguide structure was simulated and designed. Onthe basis of Maxwell’s equations and the material constitutive equations, the surface plasmonin graphene was described in the dielectric function. The dispersion and gain characteristicof the surface plasmon of the longitudinal wave mode was theoretically calculated, and theresults showed that the gain characteristics related to the carrier concentration and themomentum relaxation time. The carrier concentration of graphene which relates to thechemical potential and the physical parameters can be modified by an external electric field.In addition, the refractive index and propagation constant are also involved in the design ofthe waveguide structure. So the conductivity characteristics of graphene in the terahertz ba ndwere calculated and analyzed. Calculation results show that chemical potential affectsgraphene’s conductivity characteristics and further affects the dielectric characteristics ingrapheme. Graphene surface plasmon-based transmission structures are de signed by changeof the conductivity distribution in graphene. The transmission characteristics ofgraphe ne-based surface plasmons in different conductivity regions were simulated with theradio frequency (RF) mod ule of the COMSOL software. The results indicates that thetransmission of grapheme-based surface plasmon only exists in proper conductivity region.Y-shape waveguide based on the trans mission of Graphene-based surface plasmon issimulated and designed by applying different external voltages.更多还原