Research Of Integrated Optical Waveguide Device Based On Graphene Surface Plasmon Polaritions

In this thesis,two kinds of optical waveguide devices were designed based on graphene surface plasmon.Based on the basic theory of electromagnetic field,we make a brief introduction of basic concepts and featuresof the graphene surface plasmon.Using graphene Drude model,the dispersion relationship of air-graphene-dielectric interface plasmon structure and the transmission characteristics of graphene surface plasmon polaritons?GSPPs?wave in the grating structure waveguide are analyzed.The characteristics of proposed graphene optical waveguide devices are analyzed using with the finite element.We calculate the conductivity and permittivity of graphene under different chemical potential in terahertz?THz?frequency range.The influence of bias voltage and dielectric thickness on graphene chemical potential is studied to choose the permittivity satisfied the condition of surface plasmon.According to the characteristics of graphene surface plasmon,the novel frequency splitter based on graphene plasmonic waveguide with composite periodic grating is proposed to control the transmission of GSPPs wave.We calculate the graphene dispersion relation with the different grating period by the finite element method and choose two different periods as the branch of waveguide.The GSPPs modes with different eigenfrequencies are supported in the different periodic grating waveguide due to the dispersion relation depended on the geometric structure.The GSPPs wave can be separated into the two independent branches.The rainbow trapping is demonstrated in graphene-coated As₂S₃ optical microfiber with gradually increasing the period of the grating.The dispersions and cut-off frequency of GSPPs with different periods of gratings are analyzed.The grating structure shows strong light localization capability as the dispersion curve approaches cut-off frequency.The group velocity of GSPPs wave can be reduce to five hundred times smaller than light velocity in vacuum.The GSPPs mode at different frequencies can be localized at different positions of microfiber along the graphene surface as the cut-off frequency of the GSPPs mode varies with the position along the microfiber.