On-demand manipulation of the plasmon dephasing time plays critical roles in many important applications of localized surface plasmon resonance. Here, we systemically investigate the influence of the far-field coupling on plasmon dephasing time in different nanostructure arrays supporting single or multiple modes by for the first time applying the harmonic oscillator analysis model combined with the finite-difference time-domain numerical simulation. The results show that the dephasing time of a bright mode in the nanodisk array can be well on-demand manipulated based on the far-field coupling through varying the individual nanodisk size and array period. In particular, the dephasing time of nanodisk array with adjusting periods exhibits the behavior of first increasing and then decreasing, and it is also modified to different extents under different nanodisk sizes. Furthermore, for the heptamer array supporting multiple modes, we demonstrate that the influence of array period on dephasing time also exists for a bright mode, but a negligible effect appears for dark mode due to the negligible far-field coupling. These findings provide a potential solution to manipulate the dephasing time of plasmonic nanostructure and thereby offer flexible controllability of the ultrafast on-off process of plasmonic switching and photocatalytic efficiency.

在局部表面等离振子共振的许多重要应用中，按需操纵等离激元移相时间起着至关重要的作用。在这里，我们首次应用谐波振荡器分析模型与有限差分时域数值模拟相结合，系统地研究了远场耦合对支持单模或多模的不同纳米结构阵列中等离激元相移时间的影响。结果表明，基于远场耦合，通过改变单个纳米盘的大小和阵列周期，可以很好地按需操纵纳米盘阵列中亮模式的移相时间。特别是，具有调整周期的纳米磁盘阵列的移相时间表现出先增大后减小的行为，并且在不同的纳米磁盘大小下也对其进行了不同程度的修改。此外，对于支持多种模式的七聚体阵列，我们证明了对于亮模式也存在阵列周期对移相时间的影响，但是由于可忽略的远场耦合，对于暗模式而言，其影响可忽略不计。这些发现为操纵等离激元纳米结构的相移时间提供了一种潜在的解决方案，从而为等离激元转换的超快开-关过程和光催化效率提供了灵活的可控制性。