Research Of Graphene Based Surface Plasmon Polaritons 2D Photonic Crystals Devices For Terahertz Applications

Graphene surface plasmons polaritons(SPPs)have strong optical confinement properties.Compared to noble metal,graphene has great advantages in terahertz and mid-infrared bands include of loss control and dynamically bias voltage tunningability.Utilizes the research of 2D photonic crystals,graphene can build many novel SPP devices.In this paper,graphene SPP biasing structures have been researched and a series of graphene 2D(quasi)photonic crystals devices have been designed in terahertz and mid-infrared bands.1.The Dots Density Renderer(DDR)structure is proposed.In previous research of graphene SPP devices,the performance damage introduced by the bias structure was less concerned.This paper discusses the problem of graphene bias pattern distortion caused by bias structure,namely the "soft boundary" effect.To improve this problem,DDR structure is proposed in this paper.The structure uses the density gradient of high index points to simulate the refractive graded-index materials,thus avoiding the complex structural parameters and improving performance of graphene devices.2.A DDR based graphene SPP slow light waveguide is proposed.The 45 degrees square lattices line defact 2D photonic crystals waveguide is employed as slow light structure.By optimizing the structural parameters,the largest NDBP structure operated in the first forbidden band is found.Meanwhile,the electrical reconfiguration ability of this device is studied by tunned bias voltage.And the advantages of this slow light waveguide as an optical buffer device are discussed.3.A graphene-based wavelength division multiplexer(WDM)for terahertz SPP waves is proposed.By studying the frequency response of the single-row coupling structure of graphene SPP photonic crystal waveguide,the maximum wavelength division multiplexing number of this structure is analyzed.Then a four-frequency WDM is designed.Compared with the traditional WDM,this structure has continuous electrical reconfiguration characteristics.4.Two kinds of 2D quasi-photonic crystal devices on the graphene SPP platform using the DDR structure are designed.By studying the absorption characteristics of graphene SPP,a broadband electromagnetic absorber(electromagnetic fences)in the terahertz band is designed.This device can achieve broadband isolation on graphene SPP platform.Meanwhile,the influence of dots density on SPP transmission characteristics is also studied.Then the dots density design guidelines of the DDR structure are summarized.Based on these guidelines,the DDR based Luneburg lens and Maxwell lens are designed.