Plasmonic Lens Made of Multiple Concentric Metallic Rings under Radially Polarized Illumination
Plasmonic Lens Made of Multiple Concentric Metallic Rings under Radially Polarized Illumination
复制标题
DOI：
10.1021/nl903145p
复制
发表时间：
2009-12-01
期刊：
影响因子：
10.8
通讯作者：
Zhan, Qiwen
中科院分区：
文献类型：
--
作者：
Chen, Weibin;Abeysinghe, Don C.;Zhan, Qiwen
最佳等离子体聚焦可以通过将等离子体透镜的旋转对称性与径向偏振照明的偏振对称性匹配来实现。本文报道了用收集模式近场扫描光学显微镜对由多个同心圆环构成的等离子体激元透镜的聚焦特性和场增强效应的实验证实。在所有方位角方向上激发的表面等离子体激元向几何中心传播，并在焦点处相长干涉，产生强烈增强的倏逝光学“针”基本上垂直于等离子体透镜表面偏振的场。场增强因子可以通过在保持等离子体焦斑尺寸的同时添加更多的环来提高。采用解析和数值方法研究了场增强因子的优化策略。
Optimal plasmonic focusing can be achieved through matching the rotational symmetry of the plasmonic lens to the polarization symmetry of a radially polarized illumination. In this letter, we report the experimental confirmation of the focusing properties and field enhancement effect of plasmonic lens made of multiple concentric annular rings using a collection mode near field scanning optical microscope, Surface plasmons excited at all azimuthal directions propagate toward the geometric center and constructively interfere at the focus to create a strongly enhanced evanescent optical "needle" field that is substantially polarized vertically to the plasmonic lens surface. The field enhancement factor can be improved through adding more rings while maintaining the plasmonic focal spot size. Strategy for optimizing the field enhancement factor is studied with both analytical and numerical methods.