Effect of Symmetry Breaking on Plasmonic Coupling in Nanoring Dimers
Effect of Symmetry Breaking on Plasmonic Coupling in Nanoring Dimers
复制标题
对称性破缺对纳米环二聚体等离子体耦合的影响
DOI：
10.1007/s11468-020-01178-8
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发表时间：
2020
期刊：
影响因子：
3
通讯作者：
Lin Jingquan
中科院分区：
文献类型：
--
作者：
Dana Bereket Dalga;Koya Alemayehu Nana;Song Xiaowei;Lin Jingquan
打破金属纳米粒子（NP）二聚体的形态和组成对称性为调制纳米粒子之间的等离子体耦合提供了一种新的方法。在本研究中，我们从理论上研究了对称破缺对形态不对称的金纳米-纳米圆盘（NR-ND）二聚体、组成不对称的金-银纳米环二聚体以及组成和形态不对称的金-银纳米- nd异源二聚体的等离子体耦合的影响。发现当对称Au - NR二聚体的内半径减小时，耦合键模式和高阶耦合键模式的散射光谱强度分别急剧减小和增大。此外，还研究了宽高比对等离子体共振模式的影响。此外，在一个NR的几何参数固定的情况下，通过内半径将另一个NR的形状变形为ND，我们展示了Fano共振的产生和修改。由于分别引入了形态不对称和成分不对称，散射光谱呈现出单一的fano型光谱特征。我们证明了双对称破缺在组成和形态上不对称的异二聚体中可以很容易地实现双范诺共振。Ag NP的偶极亮模式（局域LSPR模式）与Au NP的四极子模式和六极子模式（带间跃迁）的干涉引起了这些双模。最后，在最佳的非对称异二聚体下，我们讨论了折射率对fano型共振的影响。这些新的和简单的设计为调制光学响应和产生高阶范诺共振提供了新的见解，这在光子学和折射率传感等领域具有许多潜在的应用。
Breaking the morphological and compositional symmetries of metallic nanoparticle (NP) dimers provides a novel approach to modulate plasmon coupling between the NPs. In this study, we theoretically investigate the effect of symmetry breaking on the plasmonic coupling in morphologically asymmetric Au nanoring-nanodisk (NR-ND) dimer, compositionally heterogeneous Au-Ag nanoring dimer, and compositionally as well as morphologically asymmetric Au-Ag NR-ND heterodimers. It has been found that when the inner radii of symmetrical Au NR dimer is decreased, the scattering spectral intensity of coupled bonding mode and higher-order coupled bonding mode drastically decreases and increases, respectively. Besides, the effect of aspect ratio on the plasmon resonance modes is investigated. Furthermore, with fixed geometric parameters of one NR and by morphing the shape of the other NR into ND through inner radius, we show the generation and modification of a Fano resonance. As a result of introducing morphological and compositional asymmetry separately, single Fano-type spectral feature is observed in the scattering spectra. We demonstrate that the double Fano resonances can be easily achieved in compositionally and morphologically asymmetric heterodimer with double symmetry breaking. These dual modes are caused by the interference of dipolar bright mode (localized LSPR modes) of Ag NP with the quadrupole and hexapole modes (interband transitions) of the Au NP. Finally, at optimum asymmetric heterodimers, we discussed the effect of refractive index on the Fano-type resonance. These new and simple designs provide a novel insight to modulate optical response and the generation of higher-order Fano resonances, which have many potential applications such as in photonics and refractive index sensing.