银纳米三棱柱二聚体的光学性质研究

摘要

本文利用离散偶极子近似方法研究了银纳米三棱柱二聚体的光学性质,考察了粒子相对位置、粒子间隔和入射光偏振方向对消光谱和电场的影响.入射光偏振对二聚体的消光谱和表面电场均有较大的影响.纳米粒子间隔较小时,粒子间存在较强的耦合；粒子间隔较大时,二聚体的消光谱更接近两个相互独立的粒子情形.另外二聚体的表面电场分布和平均电场强度还受到粒子相对位置和间隔的影响,随着粒子间隔的增大,表面平均电场值振荡上升达到最大值后减小.%In this paper, the discrete dipole approximation (DDA) method is used to calculate the optical properties of the nano-dimer of silver triangular prisms. The effects of the geometric configuration of the particles and the incident light polarization on the extinction spectrum and electric field distribution are examined. It is found that the incident light polarization impacts greatly to the extinction spectra and E-field. When the particle interval is large, the extinction spectrum of the dimer is close to that of the single nano-particle. In addition, the surface E-field distribution and the average E-field strength of the dimer are affected by the relative positions and distances between the particles. As the interval increasing, the average E-field first increases to the maximum and then decreases.