Burrows Christopher P, Barnes William L
School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom.
Opt Express. 2010 Feb 1;18(3):3187-98. doi: 10.1364/OE.18.003187.
We explore the optical response of two-dimensional (2D) arrays of silver nanoparticles, focussing our attention on structures for which the individual particles in isolation support both dipolar and quadrupolar localised surface plasmon modes. For individual spheres we show that when dipolar and quadrupolar modes are excited simultaneously, interference leads to most of the scattered light being radiated in the forward direction. This is in contrast to what happens when each mode is excited on its own. We further show, using finite-element modelling that when such particles are assembled into square 2D arrays, the dipolar and quadrupolar modes can combine to produce a single peak in the optical density of the array. By simulating the field distributions associated with these modes we are able to illustrate the dual-mode character of this feature in the optical density. We have extended our examination of this effect by considering how the optical density of these arrays changes with incident angle for two polarisations (s and p).
我们研究了银纳米颗粒二维（2D）阵列的光学响应，重点关注那些孤立的单个颗粒同时支持偶极和四极局域表面等离子体模式的结构。对于单个球体，我们表明，当偶极和四极模式同时被激发时，干涉会导致大部分散射光向前辐射。这与每种模式单独被激发时的情况形成对比。我们进一步通过有限元建模表明，当这些颗粒组装成方形二维阵列时，偶极和四极模式可以结合，在阵列的光密度中产生一个单一峰值。通过模拟与这些模式相关的场分布，我们能够说明光密度中这一特征的双模特性。我们通过考虑这些阵列的光密度如何随两种偏振（s和p）的入射角变化，扩展了对这种效应的研究。
