金属纳米颗粒双圆环阵列的表面格点共振效应

Surface lattice resonance effect of double-ring array of metallic nano-particles

由金属纳米粒子构成的周期性规则阵列,可以通过粒子间的耦合来激发表面格点共振效应,从而极大压缩单粒子的局域表面等离子体共振效应的线宽.本文将该表面格点共振效应从二维周期性结构推广到轴对称的圆环结构中,提出了双圆环金属纳米粒子阵列结构的电磁响应模型.在此基础上,得到了双圆环阵列发生表面格点共振效应的条件,并发现当阵列结构参数满足特定条件时,该阵列的所有偶极子分量会发生集体共振效应,从而获得极高的近场增强因子.

Surface lattice resonances due to regular periodic array of metallic nanoparticles can be attributed to the mutual coupling between the localized surface plasmon resonances of different nanoparticles.A comparison of resonant effect between the single particle and the array shows that the resonance line width can be significantly reduced.In this paper,we extend the coupled dipole approximation to solving the electromagnetic characteristics of the particle ring structures with rotational symmetry,and propose an analytical model for the double ring array of metallic nano-particles.Furthermore,we derive the general resonant condition of the double ring array and investigate some concrete cases in detail.It shows that the full resonance of the whole array depends crucially on the structural parameters,whose enhancement factor can be extremely high.But a slight change in the structural parameter willlead the enhancement factor to decrease sharply.We also find that the radiation field of the full resonance effect will be independent of the external field,which provides us a simple approach to producing a localized optical field with complex space distribution.This proposed structure can possess potential applications in various fields such as metasurface,optoelectronics,optical manipulation,communication,and biosensing.