Research On The Sensitivity Enhancement Mechanism And Optimal Design For Surface Plasmon Resonance Sensor

Optical sensors are measured based on optical principles,with the advantages of noncontact,nondestructive,anti-electromagnetic interference,high-speed transmission,telemetry,remote control,etc.Global and China's optical sensor market scale increases year by year.Although the growth rate of China's optical sensor market is still considerable in the future,due to the low level of development of China's optical sensor industry,core patents and manufacturing technology have long been monopolized by foreign countries.Surface plasmon resonance(SPR)in reflective optical sensors are widely used in food safety,environmental detection,medical diagnosis,and other fields due to their good stability,small size,good real-time,and so on.However,the traditional metal film SPR sensor has problems such as low sensitivity,poor comprehensive performance,and a great influence on the external environment.In this paper,the sensitization mechanism of the SPR sensor based on angular and phase modulation is studied,and the sensitivity of the SPR sensing structure is improved by adding new materials with excellent photoelectric properties.In addition,the optimal sensitivity and accuracy of the new structure are obtained by an intelligent optimization algorithm,which changes the time-consuming and inefficient problems of traditional SPR sensor structure design,greatly improves the efficiency of multi-layer SPR sensor design and performance analysis,and provides a platform for SPR sensor intelligent design.On this basis,a new SPR light reflection modulator with high modulation depth and low insertion loss based on the epsilon near-zero(ENZ)effect is proposed.The main work of this paper is as follows:(1)Highly sensitive SPR structure based on indium tin oxide(ITO)and two-dimensional materials(2DM)was proposed.Based on the photoelectric properties of ITO and 2DM,such as high conductivity,high carrier mobility,high transmittance,and adjustable energy band gap,two new Kretschmann structure SPR sensors were designed.Based on the transfer matrix method and Fresnel equation,angular and phase modulation of multilayer SPR sensing structures are studied.The results show that the sensitivity of the two new SPR sensing structures is significantly higher than that of the traditional Ag-SPR sensing structures.(2)An intelligent optimization method for SPR sensing performance based on adaptive fitness positive elimination mechanism,adaptive dynamic inertia weight,asynchronous learning factor and hybrid concept of genetic algorithm for particle swarm optimization(PSO)algorithm is proposed.In order to solve the problems of slow convergence speed,easy to fall into local optimum and poor global search ability of PSO algorithm in the design of SPR sensor sensitization,adaptive fitness positive elimination mechanism,adaptive dynamic inertia weight,asynchronous learning factor and hybrid concept of genetic algorithm are introduced into PSO algorithm,so as to enhance the ability of global search and local improvement and accelerate the convergence speed of the algorithm.The angular sensitivity and optimal coefficient of the new transition metal dichalcogenides(TMDCs)-graphene hybrid structure was optimized by the fitness positive elimination mechanism(FPEPSO)algorithm,and compared with the fixed variable parameter scanning(FPS)method.In order to verify the wide applicability of intelligent optimization algorithms,the FPEPSO algorithm is implemented to optimize and analyze the sensitivity of a new multi-layer SPR gas sensor,which is compared with the standard PSO algorithm.The results show that:compared with the standard PSO algorithm,the proposed FPEPSO algorithm has a significant improvement in computational efficiency.(3)Differential evolution(DE)algorithm based on chaotic mapping,fitness inverse elimination mechanism,nonlinear scaling factor,and cross probability factor control strategy is proposed to realize the intelligent optimization design of Goos-H(?)nchen(GH)shift.In order to solve the problem that the DE algorithm is easy to fall into the local optimal solution,chaotic mapping,fitness inverse elimination mechanism,nonlinear scaling factor,and cross probability factor control strategy are introduced into the DE algorithm,so as to maintain the diversity of the population,accelerate the convergence speed,and enhance the global search ability of.Based on the chaotic mapping differential evolution(CMDE)algorithm,the GH shift and sensitivity of the SPR sensors are optimized and analyzed,and compared with the FPS method.Ultimately,the CMDE algorithm and the standard DE algorithm are compared and analyzed.The results show that:compared with the FPS method,the proposed CMDE algorithm has significantly improved the GH shift and sensitivity;compared with the standard DE algorithm,the proposed CMDE algorithm has a significant improvement in computational efficiency.(4)SPR broadband optical reflective modulator with high modulation depth and low insertion loss based on ENZ effect is designed.In order to verify the wide application of SPR structure,a SPR broadband optical reflection modulator is designed based on the dielectric constant zeroing effect of ITO.The modulator is composed of vertical layers,which are easy to manufacture and simple techniques,and numerical simulation is carried out.Driven by the external voltage,the free carrier-concentration-dependent permittivity of ITO at the Hf O₂/ITO interface induces an ENZ effect contributing to strong field enhancement and modifies the SPR condition of the incident light.High modulation depth and low insertion loss can be obtained by optimizing the geometric parameters and appropriate carrier concentration design.Subsequently,the effects of carrier concentration,the thickness of silicon,and wavelength on the modulator performance were studied.By optimizing the structure parameters,about 100%modulation depth and 3.7%insertion loss can be obtained simultaneously.