异质铝/金二聚物和三聚物中的等离子耦合性质

The Coupling of Plasmon of Hetero-Al/Au Dimer and Trimer

采用时域有限差分方法研究了异质铝/金二聚物和铝/金/铝纳米线三聚物的光学性质.首先研究了二聚物和三聚物的间距对透射谱和电场分布的影响,发现随着间距的增大,原短波长透射峰增强,并在间距大到一定程度时,发生分裂现象,而长波长透射峰在这个过程中单调红移.通过分析电场分布,我们发现分裂的峰之一是一种新的等离子耦合模式.另外,我们也分析了半径变化和金线偏移中心量对三聚物透射谱的影响,其中左侧铝线的半径变小会使近红外和红外区域的两个峰合并,而金线半径变小却会使它们两个峰分裂得更明显;另外我们发现金线偏移中心对透射增强不利.这些结果对铝/金异质聚合物的制作可能有理论指导作用.

We investigate optical properties of the hetero- AI/Au dimer and A1/Au/A1 trimer by means of FDTD method. Firstly, we study the influence of gap distance on the transmission spectra and field distri- bution. Ifs demonstrated that as the gap distance increases, the original shorter wavelength peak enhances and splits as distance is large enough, but the longer wavelength peak redshifts monotonously. Through our analysis, we find that the new existing peak is a new plasmon coupling modes. In addition, we study the effect of the radii and the Au nanowire center-offset value the transmission properties. The results show that as the left A1 nanowire radius becomes smaller, the peaks in the near-infrared an infrared merge, while as the Au nanowire becomes smaller, the two peaks split more obvious. We also find that the offset of the Au nanowire is not good for enhance transmission. Those results provide theoretical guidance for fabricating the Al/Au hetero-oligmer.