Research On Surface Plasmon-induced Transparent And Dimmable Switches

Surface plasmons are electromagnetic waves formed by collective oscillations.They are caused by the coupling of incident electromagnetic waves with free electrons on the metal surface.Surface plasmons have the characteristics of breakthrough diffraction limits,which allow them to propagate at sub-wavelength scales,which can be applied to large-scale integrated optical paths.The metal surface plasmon structure is simple and widely used,and can be used for plasmon-induced transparency and plasmon sensing.Graphene surface plasmons associate surface plasmons with the terahertz band,reducing losses,improving transmission efficiency,and enabling regulation.In this paper,based on the metal surface plasmon and graphene surface plasmon,the rectangular ring structure waveguide,the nonlinear material ring waveguide and the electrically tunable graphene optical switch are designed,and the transmission characteristics are analyzed.The main contents of this article are as follows:(1)Briefly introduced the discovery,nature and characteristics of surface plasmons,and the background and development status of the research.(2)The wave equation of metal surface plasmon is introduced from the metal free electron gas model.The expression forms and characteristic properties of surface plasmons in single interface and multi-interface systems are introduced respectively.Finally,the metal is introduced.Several common excitation methods for surface plasmons.(3)Based on the electronic band structure of graphene,the conductivity of graphene is derived.The expression of graphene surface plasmon is introduced,and the single layer graphene,multilayer graphene and graphene-metal hybrid are introduced,respectively.The patterns of graphene surface plasmons in different structures were analyzed,and the characteristics of graphene surface plasmons in different structures were introduced.(4)A metal-insulator-metal(MIM)plasmon waveguide with two rectangular ring-shaped structures was designed.The influence of geometric parameters on the transmission spectrum was analyzed by numerical simulation.The results show that the transparent window can be adjusted by changing the geometric parameters.(5)The MIM waveguides with the upper and lower discs are designed.The influence of geometric parameters on the transmission spectrum is analyzed.Then,nonlinear materials are introduced into one disc,and the influence of pump light intensity on the transmission spectrum is analyzed.The results show that the geometric parameters of thestructure will have an effect on the transmission spectrum.Moreover,the addition of nonlinear materials allows the structure to achieve a specific wavelength filtering effect.(6)An optical switch based on graphene hybrid waveguide is designed.The coupling length of the waveguide and the influence of geometrical dimensional change of graphene on port transmission are analyzed.The results show that by adjusting the Fermi level of graphene in the structure,the switching and splitting of incident light at a specific wavelength can be achieved.At the same time,when the geometrical dimensions of graphene change,the Fermi level of graphene can be adjusted.To ensure that the device can achieve the same function.