Interaction Studies Of Surface Plasmons In Metal Nanocomposite Structures

Under the action of incident light,the free electrons on the surface of metal nanostructures are excited,resulting in electromagnetic wave propagating along the metal surface,which is called surface plasmon.Due to its unique properties,surface plasmons have become a research hotspot in physics,chemistry,biology and other fields.In recent years,with the rapid development of nanotechnology,coupled with exquisite structure processing technology,various metal nanocomposites have been manufactured.It is found that the evolution behavior of metal nanocomposites can be explained theoretically by adjusting the physical parameters.This paper mainly studies the following two composite structures.1.The interaction between plasmons on the surface of the microstructure unit composed of silver nanoring and silver nanorod is studied by using the harmonic oscillator coupling model.A new physical model is proposed to describe the influence of Coulomb potential and electrostatic potential(CPEP)on coupling coefficient and frequency offset.Based on the finite element method,the asymmetric evolution of the absorption spectra of the micro unit structure are simulated with the change of the coupling distance between the silver nanorod and the silver nanoring.Using the CPEP model and the new physical quantity frequency offset defined,not only the asymmetric behavior of the resonance absorption peaks with the change of the coupling distance between the silver nanounit structures is successfully explained,but also the resonance frequencies of the plasmon corresponding to the different coupling distance is obtained.It can be seen that the coupling process of plasmons can be well explained by harmonic oscillator coupling model combined with Coulomb potential and electrostatic potential.2.Interaction between ring/multi split ring silver nanostructures.Based on the finite element method,the absorption spectra,distribution of electric fields and charges of the structure under the excitation of incident light are simulated.It is found that the frequencies anticrossing is obvious by adjusting the angle of split-ring and coupling the evolution of resonance absorption spectra.The anticrossing characteristic of the eigenfrequencies of the coupling oscillator is described by using the coupling model of the harmonic oscillator,and the result are consistent with the numerical result.