Surface Plasmon Waveguide Characteristics Analysis And Its Application Research

Surface plasmon polaritons(SPPs)are transverse magnetic electromagnetic modes at nanoscale,which are induced by the coupling of the incident light and the free electron of metal and propagate at the interface between dielectric and metal.Surface plasmon polaritons have high mode volume and can break through diffraction limitation at nanoscale,which provide a promising approach to manipulate light in nano-scale.Graphene,as a special 2-D material,has special optical and electrical propriety,and can produce surface plasmons polarition at THz wavelength with lower propagation loss and high light confinement.In this thesis,we will use noble metal and grapehene separately to design plasmonic waveguide,nano-disk resonace cavity,waveguide array and analyze the optical properities,such as waveguide coupling,nano-disk resonace,periodic imaging and so on.Following is the main content of this thesis:(1)The research background,the development and characteristic parameters of SPPs were introduced in the 1st Section.(2)The dielectric function of the free electron gas(Drude mode),excited method of SPPs and the simulated numerical method: Finite Element Method(FEM)were introduced in the Section 2.(3)In section 3,a novel hybrid plasmonic waveguide with a spherical cap was designed and its light confinement and propagation length were studied.The simulation result shows that the designed plasmonic waveguide can realize tighter light confinement and relatively long propagation length.(4)A noninear hybrid plasmonic waveguide with a metal cap was proposed in Section 4.By analyzing the relation between the optical properities,effective area,figure of merit,effective nonlinearity coefficient,the propagation,and geometric dimension and the nonlinear material,the optimal waveguide structure and the best nonlinear material can be confirmed.(5)A novel multi-wavelength band-pass plasmonic splitter with two nanodisk cavity was designed in the 5th Section.According to resonant theory and the waveguide coupling theory,simulation result shows that the resonant wavelength can be changed by varying the dimeters of nanodisk(r1?r2),the transmission can be changed by varying the distance(d)between nanodisk and the straight waveguide.(6)In the 6th Section,the properity of graphene and the current research background of graphene surface plasmons polaritons were introducted.Based on this,we designed a novel hybrid graphene plasmonic waveguide.The mode effective index,propagation length,cut-off wavelength and the related geometric dimension are analyzed.Based on this,we proposed an electrically tunable optical switch,and analyze its transmission.The simulation shows the designed optical switch can realize on-off function for different graphene Fermi energy.(7)A dielectric graphene plasmonic waveguide array was designed in the Section 7,and the super-modes and their propagation constants were calculated in detail.Based on the super-mode theory,we first introduce the theory of superposition of different super-modes,and realized the Talbot Effect in dielectric graphene plasmonic waveguide array.The relations between graphene Fermi energy,distance of waveguides and the Talbot Distance were analyzed based on theory and simulation.The simulation results show a good aggrement with theoretical analysis,which verify the theory of superposition of different super-modes.This work extends the Talbot effect to a new platform and potential applications in developing graphene-based imaging devices at nanoscale.