领结状金纳米二聚体耦合共振特性研究

Investigation on localized surface plasmon resonance in bowtie gold dimer

利用有限元法对领结状金纳米二聚体结构的表面等离激元共振特性进行了探究,研究发现在几何形状保持不变的条件下,二聚体共振波长位移与粒子间距呈e的负指数变化,并且指数衰减系数与粒子大小无关。进一步分析了纳米结构附近电场分布,发现共振条件下单体结构的x轴和y轴电场分布都遵守e的负指数衰减规律,且场强与入射电磁波的偏振方向有关;而受二聚体间表面等离激元耦合因素的影响,二聚体之间的距离对场强的衰减速率有着巨大的影响。最后,对二聚体共振吸收强度进行了研究,发现吸收强度与二聚体距离之间的关系仍为e的负指数函数规律。本研究结果对微距传感、粒子捕获等具有重要的指导意义。

The localized surface plasmon resonance of bowtie gold dimer are numerically simulated by finite element method in this work.It is found that when the geometry remains unchanged,the resonant peak shifts of gold dimer decay exponentially with increasing particle spacing,and the decay length is size-independent as the shift and gap are scaled respectively by the peak wavelength and particle size.The electric field distribution of the nanostructures under the resonance condition is further analyzed.It is found that the electric field distribution along the x and y axes of the single obeys the law of negative exponential decay,and the intensity of the electric field is related to the polarization direction of the incident electromagnetic wave.While due to the coupling effect of surface plasmon between dimers,the gap between dimers has a great influence on the attenuation rate of the electric field.Finally,the resonance absorption inensity of dimers is also studied,and it is found that the relationship between the absorption inensity and the gap of dimer is still a negative exponential function.The results of this paper have important guiding significance for micro sensing,particle capture,and so on.