Quantum Nonlocal Electromagnetic Properties Of Typical Metal Nanostructures

Metal nanostructures based on Localized Surface Plasmon（LSP）and Surface Plasmon Polariton（SPP）effects have been widely concerned by researchers,and have been applied in biomolecular detection,integrated photon chip,solar cells,optical storage and other fields.With the continuous improvement of manufacturing technology,the size of nanostructures is getting smaller and smaller,and new features are emerging,such as quantum properties and nonlocal properties.Therefore,it is necessary to use new theories to study the electromagnetic properties.Based on this,the Finite Element Method（FEM）is used to study the electromagnetic properties of surface plasmon metal nanostructures in theory,and the quantum nonlocal properties of metal nanostructures are mainly discussed..The main research work of this dissertationis as follows:1. Starting from Maxwell’s equation and quantum hydrodynamics equation,the self consistent coupling equations for solving the response of free electrons to external electromagnetic field are derived in detail.On this basis,the classical electromagnetic model,the traditional nonlocal model,the quantum dynamics theoretical model and the quantum correction model corresponding to different size structures are given,and a set of solutions for different sizes are established Quantum nonlocal properties of metal nanostructures.2. Based on the nonlinear medium Si-NC/Si O₂,a hybrid surface plasmon waveguide is designed.The effects of the geometry and nonlinear factors of the waveguide on the effective refractive index,propagation length and effective area of the fundamental mode are studied,and the structure is optimized according to the research results.By improving the structure of the waveguide,the nonlocal characteristics caused by spatial dispersion are further studied.On the one hand,the research results are helpful to understand the mode distribution and transmission characteristics of surface plasmon waveguide,on the other hand,it provides a theoretical basis for the application of plasma waveguide in integrated optical devices.3. Based on the nonlocal dispersion model,the weak solutions of the coupled equations are derived in detail.The optical cross sections of typical two-dimensional and three-dimensional metal nanostructures are calculated.According to the calculation results,the causes of peak shift and amplitude variation are explained in theoretically and the application range of the nonlocal dispersion model is analyzed.4. The Quantum Hydrodynamic Theory（QHT）is derived in detail,the influence of different internal functional terms on the density distribution of ground state electron is studied,and the results are applied to calculate the optical cross section of typical two-dimensional and three-dimensional metal nanostructures.By comparing with the results of classical electromagnetics and Time-Dependent Density Functional Theory（TD-DFT）,the application scope of different methods is analyzed.The results show that this method is very effective for the prediction of the spectrum in the nano plasma system,which extends the current kinetic theory,and is of great significance for the study of the optical properties of metal nanostructures.5. When the distance between the nano dimers is reduced to sub nanometer level,it is necessary to consider the effect of electron tunneling on its optical properties.In this dissertationis,a simple and effective method is proposed,which combines the classical electromagnetic calculation model with the quantum mechanical effect.Firstly,the quantum correction model is deduced in detail,and a virtual effective material layer selection method is proposed.Secondly,the QCM model is applied to the calculation of the optical properties of typical two-dimensional and three-dimensional metal nano dimers.The numerical results are compared with the results of full quantum mechanics and classical electromagnetic calculation,and the results show that the reliability and accuracy of this method in the calculation of the optical properties of nano dimers are verified,and an effective method for theoretical analysis of quantum nonlocal properties of metal nano polymer structures with sub nano level spacing is constructed.