Performance Optimization Of Polygon Sensor Based On Surface Plasmon

Surface Plasmon Polaritons(SPPs)are electromagnetic Surface waves formed by the interaction of incident light with free electrons on the metal Surface.When the two frequencies resonate at the same time,the interaction between the metal's free electron and the incident photon reaches the strongest,and the energy of its electromagnetic field is bound to the metal surface,and the surface plasmon wave propagates along the interface.Moreover,surface plasmons can break through the limitation of diffraction limit.With their excellent optical properties,researchers can make the size of optical devices to micro/nano level.In recent years,surface plasma waveguides based on metal-insulator-metal(MIM)have been widely studied.This structure is more suitable for making high integration and high sensitivity optical devices to achieve flexible control of photons in the subwavelength size,such as optical switches,filters,sensors,etc.The research of this paper focuses on improving the performance of polygon sensor of MIM waveguide.Starting from a hexagonal sensor structure with good Fano resonance effect,by adding tooth cavity and arc cavity to its basic structure,the independent adjustable multiple Fano peaks can be generated on the basis of the original structure.The main content of this paper includes the following aspects:Firstly,the basic theory of surface plasmons resonance with Fano is introduced,and the basic principle of surface plasmons is deduced from Maxwell's equation.Then,the excitation mode and dispersion mode are introduced.The MIM structure,coupled mode theory(CMT)and metal DRUDE model used in the subsequent theoretical analysis of this paper are summarized.In addition,this paper describes the software COMSOL and the operating principle(FEM)of the software used in the theoretical simulation.Then,based on the theoretical knowledge above,this paper proposes a hexagonal waveguide sensor structure with independent tunability with baffle,and analyzes the structure in detail by using COMSOL software and CMT method.Moreover,the optical micro-nano structure is optimized,and two new multi-Fano structures with baffles are proposed.Both of these two structures have better sensing characteristics and adjustability on the basis of the original structure.The innovation of this paper lies in the in-depth exploration of the polygon structure,and summarizes the optimization scheme of multi-Fano for the polygon structure.The proposed structures have good sensor properties,FOM values of 4.5 × 104 and sensitivity of 1500nm/RIU.To sum up,this paper summarizes the direction of sensor optimization and proposes a new structure,which plays a positive role in promoting the future development of high integration micro/nano sensors.