纳米银立方体与银膜耦合结构的电场特性

纳米金属颗粒及其与金属膜的耦合结构具有比单元结构更优越的物理性质。为了给实验研究纳米银立方体和银膜耦合结构在传感中的应用提供理论依据，运用FDTD方法数值分析了纳米银立方体与银膜耦合体系在波长为514.5 nm的激光激发下的电场性质。结果表明，耦合结构的电场分布与纳米银立方体的大小、及其与银膜间的介质层厚度有关；纳米银立方体与银膜耦合结构局域电场比纳米银立方体的局域电场强；当其间没有介质层时，局域电场主要分布在纳米银立方体的上表面顶点；当有介质层时，局域电场会有部分转向高折射率介质层中。因此，可根据需要，通过调控纳米银立方体的大小及其与银膜间的介质厚度来获得理想的局域电场。

Electric field properties of coupled structure based on silver nanocube and silver film

The coupled structure of metal nanoparticles and metal film has more superior physical properties than unit structure. In order to provide theoretical basis for experimental study on the application of silver nanocube coupled with silver film in sensing, the electric properties of the coupled system were analyzed using FDTD excited at the wavelength of 514.5 nm. The results show that the electric field distribution of the coupled structure of silver nanocube and silver film was affected by the size of silver nanocube and the thickness of the dielectric spacer between silver nanocube and silver film. The local electric field of the coupled structure was stronger than that of unit of silver nanocube. When there was no dielectric spacer, the local electric field was mainly localized on the upper surface of the silver nanocube for the coupled structure. When there was dielectric spacer, the local electric field would be partially localized in the dielectric spacer. Therefore, the ideal local electric field can be obtained by adjusting the size of silver nanocube or the thickness of spacer between silver nanocube and silver film for requirement.