Study On Transmission Characteristics Of Surface Plasmon Polaritons Based On Graphene

At present,the maturing of optical communication technology provides a good opportunity for the development of photonic integrated devices.The effective control of interaction between matter and light at the deep sub-wavelength scale in the field of micro-and nano-photonics has caused an upsurge of research.Resonance of photons with the free electron at the surface of the metal conductor will excite the surface plasmon polaritons.It has strong locality and successfully achieved miniaturization and integration of optical transmission devices.Graphene is a new type of photoelectric two-dimensional material.Due to its unique energy band structure and electron transport properties and its compatibility with silicon-based semiconductor processes,graphene has attracted extensive attention from both academia and industry.Compared with the traditional metal surface plasmas,graphene plasmons exhibit unique properties such as electrical tunability,low intrinsic loss and strong localization of field.The resonance frequency of graphene plasmons is from Infrared to terahertz,which also is continuously adjustable.Optical waveguides and light modulators are essential components for optical systems.Therefore,on the foundation of the research of hybrid waveguides,a detailed exploration of the modulators based on graphene plasmons is carried out in this dissertation.The main work of this article includes the following aspects:(1)On the basis of extensive review of domestic and foreign literature related to graphene surface plasmons and recent research results,we offer the corresponding introduction and analysis of the research background,current status,and application prospects of hybrid surface plasmons waveguides and graphene modulators.(2)Combining Maxwell's equations with material constitutive equations,the excitation mechanism and properties of the surface plasma wave at the interface of metal and medium is given.At the same time,the modulation effects of photoconductivity with the applied electric field of graphene plasmons and dispersion relationship is deduced.The numerical simulation software COMSOL based on the finite element method is briefly introduced.(3)Based on the principle and advantages of the hybrid plasmons waveguide,the characteristic parameters of the mixed mode are described by effective refractive index,transmission distance,effective mode field area.The COMSOL was used to analyze and optimize the two-dimensional distribution of the mode field and the properties of the hybrid mode in the hybrid tube-triangle plasmonic waveguide(HTTPWG)and hybrid cylinder-triangle plasmonic waveguide(HCSPWG)proposed in this thesis.The properties of the mixed mode vary with the geometric size,the material's dielectric constant and other parameters of the waveguide structure.These studies laid the foundation for the fourth chapter of the study of graphene plasmon polariton modulators.(4)In this thesis,based on the unique advantages of graphene,several modulators with widely used single/double layer graphene and waveguide are introduced,and their performance parameters are compared.Finally,we focused on the detailed design of the optical modulator based on the double-layer graphene ring resonator and the optical modulator based on the graphene waveguide-slot hybrid plasmons.