Xu Yang, Qin Yulu, Ji Boyu, Song Xiaowei, Lin Jingquan
Opt Express. 2020 Mar 30;28(7):9310-9319. doi: 10.1364/OE.379429.
The performance of plasmon in applications is strongly related to plasmon damping, i.e., a dephasing of the optical polarization associated with the electron oscillation. Accurate measurement, manipulation, and, ultimately, prolongation of the dephasing time are prerequisites to the future development of the application of plasmonics. Here, we studied the dephasing time of different plasmonic hotspots in an individual bowtie structure by time-resolved photoemission electron microscopy and proposed an easy-to-operate method for actively and flexibly controlling the mode-dependent plasmon dephasing time by varying the polarization direction of a femtosecond laser. Experimentally, we achieved a large adjustment of the dephasing time ranging from 7 to 17 fs. In addition, a structural defect was found to drastically extend the plasmon dephasing time. Assisted with the finite-difference time-domain simulation, the underlying physics of the dephasing time extension by the structural defect was given.
等离子体激元在应用中的性能与等离子体激元阻尼密切相关，即与电子振荡相关的光极化的退相。准确测量、操控并最终延长退相时间是等离子体激元应用未来发展的先决条件。在此，我们通过时间分辨光发射电子显微镜研究了单个蝴蝶结结构中不同等离子体激元热点的退相时间，并提出了一种易于操作的方法，通过改变飞秒激光的偏振方向来主动灵活地控制与模式相关的等离子体激元退相时间。实验上，我们实现了退相时间从7飞秒到17飞秒的大幅调整。此外，还发现一个结构缺陷能显著延长等离子体激元退相时间。借助时域有限差分模拟，给出了结构缺陷延长退相时间的潜在物理机制。
