Du Guangqing, Lu Yu, Lankanath Dayantha, Hou Xun, Chen Feng
State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Nanomaterials (Basel). 2021 Mar 17;11(3):759. doi: 10.3390/nano11030759.
Plasmonic optical tweezers with a symmetry-tunable potential well were investigated based on a heterogeneous model of nano-bowtie antennas made of different noble substances. The typical noble metals Au and Ag are considered as plasmonic supporters for excitation of hybrid plasmonic modes in bowtie dimers. It is proposed that the plasmonic optical trapping force around a quantum dot exhibits symmetry-broken characteristics and becomes increasingly asymmetrical with increasing applied laser electric field. Here, it is explained by the dominant plasmon hybridization of the heterogeneous Au-Ag dimer, in which the plasmon excitations can be inconsistently modified by tuning the applied laser electric field. In the spectrum regime, the wavelength-dependent plasmonic trapping potential exhibits a two-peak structure for the heterogeneous Au-Ag bowtie dimer compared to a single-peak trapping potential of the Au-Au bowtie dimer. In addition, we comprehensively investigated the influence of structural parameter variables on the plasmonic potential well generated from the heterogeneous noble nano-bowtie antenna with respect to the bowtie edge length, edge/tip rounding, bowtie gap, and nanosphere size. This work could be helpful in improving our understanding of wavelength and laser field tunable asymmetric nano-tweezers for flexible and non-uniform nano-trapping applications of particle-sorting, plasmon coloring, SERS imaging, and quantum dot lighting.
基于由不同贵金属制成的纳米蝴蝶结天线的非均匀模型，研究了具有对称可调势阱的表面等离子体光镊。典型的贵金属金和银被视为用于激发蝴蝶结二聚体中混合等离子体模式的等离子体载体。研究表明，量子点周围的表面等离子体光捕获力呈现对称破缺特性，并且随着外加激光电场的增加而变得越来越不对称。在此，这是由非均匀金 - 银二聚体的主导等离子体杂化来解释的，其中等离子体激发可以通过调节外加激光电场而不一致地改变。在光谱范围内，与金 - 金蝴蝶结二聚体的单峰捕获势相比，非均匀金 - 银蝴蝶结二聚体的波长依赖性表面等离子体捕获势呈现双峰结构。此外，我们全面研究了结构参数变量对由非均匀贵金属纳米蝴蝶结天线产生的表面等离子体势阱的影响，这些参数包括蝴蝶结边缘长度、边缘/尖端圆角、蝴蝶结间隙和纳米球尺寸。这项工作有助于增进我们对波长和激光场可调谐非对称纳米镊子的理解，以用于粒子分选、等离子体着色、表面增强拉曼散射成像和量子点照明等灵活且非均匀的纳米捕获应用。
