Dong Jianjie, Feng Huimin, Wang Xiaofeng, Chen Shengyao, Wang Shu, Zhang Chen, Liu Qian
Chinese Academy of Sciences (CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China.
University of Chinese Academy of Science, Beijing 100049, People's Republic of China.
Nanotechnology. 2021 Oct 6;32(50). doi: 10.1088/1361-6528/ac2767.
Achieving a large enhancement of local electromagnetic fields in the ultraviolet waveband is desirable for some applications such as surface-enhanced Raman scattering and surface-enhanced fluorescence. In addition, it is more significant for some applications such as plasmon-enhanced harmonic generation to enhance the intensity of local electromagnetic fields and increase their decay time at the same time. In this paper, using the finite-difference time-domain method, we numerically demonstrate that using the linearly polarized light with a wavelength of 325 nm as the illumination light, an isolated triangular Al-SiO-Al hybrid nanoplate with optimized geometric parameters can produce a local electric field enhanced by a factor of about 108 at one of its top apexes, and produce two local electric fields enhanced by a factor of about 150 at two transverse dielectric/metal interfaces of one of its longitudinal side edges. Moreover, we also numerically demonstrate that the decay time of enhanced local electric fields produced by the isolated triangular Al-SiO-Al hybrid nanoplate is about 1.6 times as large as that of enhanced local electric fields produced by an isolated triangular Al nanoplate. These unique properties of the isolated triangular Al-SiO-Al hybrid nanoplate arise because of both the transverse coupling and the longitudinal coupling of localized surface plasmon polaritons in this structure. Our findings make triangular Al-SiO-Al hybrid nanoplates very promising for application in many fields such as surface-enhanced Raman scattering and plasmon-enhanced harmonic generation.
在紫外线波段实现局部电磁场的大幅增强，对于诸如表面增强拉曼散射和表面增强荧光等一些应用来说是很有必要的。此外，对于诸如等离子体增强谐波产生等一些应用而言，同时增强局部电磁场的强度并延长其衰减时间则更为重要。在本文中，我们使用时域有限差分法进行数值模拟，结果表明，以波长为325 nm的线偏振光作为照明光时，具有优化几何参数的孤立三角形Al-SiO-Al混合纳米板在其一个顶角处可产生约108倍增强的局部电场，并且在其一条纵向侧边的两个横向介电/金属界面处可产生约150倍增强的两个局部电场。此外，我们还通过数值模拟证明，孤立三角形Al-SiO-Al混合纳米板产生的增强局部电场的衰减时间约为孤立三角形Al纳米板产生的增强局部电场衰减时间的1.6倍。孤立三角形Al-SiO-Al混合纳米板的这些独特性质源于该结构中局域表面等离激元极化子的横向耦合和纵向耦合。我们的研究结果表明，三角形Al-SiO-Al混合纳米板在表面增强拉曼散射和等离子体增强谐波产生等许多领域具有很大的应用前景。
