Regulation Of The Photonic Spin Hall Effect On Graphene/Hexagon Boron Nitride Metasurface

Natural hyperbolic materials represented by Hexagonal boron nitride(h BN)have surface phonon polarons(SPh Ps)formed by coupling the optical mode of phonons with the incident photoelectric field,whose loss is mainly due to phonon scattering.These materials are the first choice for the development of new devices.In the mid-infrared to terahertz frequency region,the resonant frequencies of Graphene(Gr)surface plasmons(SPPs)are continuously tunable.By using natural hyperbolic material h BN as the base and graphene on top,surface isoionization phonon polaron(SPPPs)can be formed by strong coupling of surface phonon polaron and surface plasmon.The loss of the new SPPPs is much less than that of the metal SPPs.The optical properties of the new SPPPS can be controlled effectively by applying electric field and changing Fermi energy level.In this paper,the spin Hall effect of graphene/h BN hypersurface structures formed by coupling hexagonal boron nitride with graphene is theoretically studied using the equivalent medium theory,electromagnetic boundary conditions and Maxwell equations.Mainly carried out the following work:1.A tunable photonic spin Hall effect structure is constructed by introducing a layer of graphene nanoribbon onto a semi-infinite h BN.Due to the interaction between the SPh Ps in h BN and the SPPs in graphene,the spin displacement is significantly changed compared with the uncoated graphene.In the vicinity of the first residual frequency band,the spin displacement is significantly enhanced,while in the vicinity of the second residual frequency band,the spin displacement is significantly weakened.Due to the existence of deflection Angle of graphene nanoribbon,the left and right circular deflection displacements appear asymmetric phenomenon,and the spin displacement can be effectively adjusted by adjusting the deflection Angle.In addition,the regulating effects of incident light Angle,chemical potential,graphene occupancy and the number of layers of graphene nanoribbon on spin displacement were investigated.These findings provide potential applications for spin optics and photon control based nanooptical devices.2.On the substrate with h BN as the underlying base,a rectangular grating with a certain thickness is coated.The grating layer is composed of parallel rectangular h BN bars separated by graphene with equal spacing,constructing the hypersurface structure of graphene/h BN grating.By means of the transmission matrix method,the relation of electromagnetic field and Fresnel reflection coefficient are calculated,and the spin Hall effect produced by the reflected beam on the dielectric surface is further investigated.It is found that the spin displacement can be controlled by adjusting the space occupancy of graphene when the material structure is changed into grating structure.In addition,by adjusting the incidence Angle,the deflection Angle of the grating structure and the chemical potential,the magnitude of the spin displacement and the corresponding frequency position of the spin displacement can be effectively regulated.