Research Of Fano Resonance Effect Of Surface Plasmon Based On Ring-C2/C3 Hybrid Metasurface

Surface plasmons(SPs)are mainly composed of surface plasmon polaritons(SPPs)propagating along the metal surface and localized surface plasmons(LSPs)concentrated inside the metal hole structure.Metasurface is a two-dimensional metamaterial based on subwavelength nanostructures.It can control the light field by changing the geometric configuration of the unit structure,and then it is widely used in superlenses,invisible devices,high-precision biochemical sensors and so on.However,in the field of metasurfaces,the study of the Fano resonance effect induced by the whispering gallery mode(WGM)resonance with high sensitivity and high quality factor has broad application potential.This work uses the three-dimensional finite difference time domain(3D-FDTD)method to simulate the Fano resonance phenomenon based on the whispering gallery mode.The main contents are as follows:(1)The basic principles of SPs micro-nano photonics are discussed.Then Maxwell's equations is used to derive the basic properties of SPs on the metal/substrate interface at infinity.We finally introduce the Fano resonance of SPs in metasurface based on the whispering gallery mode.It also briefly summarizes the research progress of related work at home and abroad;and focuses on the basic theory of the FDTD method and the realization of the FDTD of the metal dispersion model.(2)To analyze the Fano resonance in hybrid metasurface composed of different geometric configurations,the 3D-FDTD method is used to numerically simulate the light transmission characteristics of three different structures(metal slit structure with C2-type symmetry,central ring aperture structure and ring-slit composite structure).It is found that the whispering gallery mode of the nano-ring structure can perform Fano resonance with the slit structure inside the ring to form a plasmon-induced transparency window between two peaks in the near-infrared band.By changing the geometric parameters of the hybrid structure,the position and intensity of the resonant peak and the plasmon-induced transparency window in the spectrum can be effectively controlled.(3)To obtain more resonant modes in hybrid metasurface,the3D-FDTD numerical simulation method is employed to numerically simulate the optical transmission characteristics of the central ring aperture-C3 symmetrical subwavelength hybrid hole arrays silver film on the quartz substrate.The results show that the hybrid metasurface can effectively produce double Fano resonance with four resonance modes in the near-infrared band,due to the Fano resonance arise from the ring-C3 structure,the C3-type symmetry structure and the WGM mode in the ring structure.Adjustment between single Fano resonance and multi Fano resonances can be achieved by changing arm length of C3-type symmetry structure and polarization angle of the incident light.