Research On High-Performance Sensing Devices Based On Adjustable Metasurface Structures

Sensing technology is like a new feature of human perception.As one of the three pillars of information technology,it has become an important symbol to measure the degree of informatization of the country.The refractive index sensing technology is widely used in food safety,environmental science,medical diagnosis,and other fields,and is expected to contribute to social development in the future.Among them,compared with the traditional sensing devices using natural materials,the refractive index sensor based on the metasurface has strong light field manipulation capabilities,which can achieve flexible control of the light and stimulate special electromagnetic responses.At the same time,metasurface is smaller in size,has less loss,is easier to integrate than traditional sensing devices,and can even be integrated into the chip.Metasurface can not only improve detection accuracy,but also reduce time and cost,so it has a competitive advantage in the field of sensors.Based on the FiniteDifference Time-Domain Method,this article uses basic theories such as restraint and basic electromagnetic source decomposition in the continuous domain and takes the super surface sensor performance research as the core.Research on parameter adjustment,performance optimization,function expansion,etc.The research is based on the Finite-Difference TimeDomain method,bound states in the continuum,and electromagnetic multipole expansion theory.The main research content in this article is the sensor analysis of the metasurface.Based on this theme,the excitation,mechanism analysis,parameter adjustment,performance optimization,and function expansion of high Q-factor multi-Fano resonance in metasurfaces are studied.The main research content is as follows:(1)We designed a series of pinwheel-shaped all-dielectric metasurfaces.By introducing the asymmetric parameter,multiple Fano resonances are stimulated in the original pinwheel-shaped all-dielectric metasurface and realize the resonance mode of magnetic dipoles(MD),toroidal dipoles(TD),electric quadrupoles(EQ),etc.The maximum Qfactor reaches 3.91×104.The sensitivity and the figure of merit(FOM)could respectively reach up to 355 nm/RIU and 1375.97 RIU-1 through the polarization angle adjustment and using three substrate etching files.The simulation results show that the structure has excellent sensing characteristics.By changing the polarization angle of the incident light,we studied the good optical switch characteristics and flexible geometric parameters tunability of the structure.Later,based on the original pinwheel-shaped all-dielectric metasurface,we designed the improvement of the pinwheel-shaped all-dielectric metasurface.Based on keeping the resonance mode almost the same,the sensitivity of the Fano resonances has been promoted overall.The series of pinwheel-shaped all-dielectric metasurfaces may provide a way to enhance the performance of biochemical sensors,optical switches,and nonlinear optics.(2)We proposed the metasurface based on cross cracks and an ellipse hole.In the all-dielectric metasurface,we have introduced the asymmetric parameter to stimulate multiple sharp Fano resonances and achieve a variety of electromagnetic response modes including magnetic quadrupoles(MQ).We researched and analyzed its sensing performance and geometric parameters,and achieved the maximum sensitivity of 323.25 nm/RIU and the figure of merit of 1240.91 RIU-1.By adding the metal aluminum substrate,we designed the dielectric-dielectric-metal(DDM)extension structure.This structure stimulates multiple narrowband absorption peaks with high absorption rates,with the highest absorption rate close to 100%,and the best FWHM reaching 0.29 nm.Based on the FWHM formula analysis,geometric parameters are adjusted to realize the flexible adjustment of the absorption peak FWHM.