Wu Jiepeng, Zhang Fanwei, Li Qiang, Feng Qianbin, Wu Yu, Wu Lijun
Opt Express. 2020 Jan 6;28(1):570-579. doi: 10.1364/OE.381648.
Due to their ability to produce high electric field enhancements in relatively large nanoscale volumes with minimum absorption and nonradiating properties, anapole modes excited in high index dielectric nanostructures have attracted considerable attentions in these years. We propose a design strategy to simultaneously excite the anapole mode efficiently and maintain its resonant wavelength, which has been remained as a challenge in the conventional dielectric nanostructures. Based on analyzing the relationship between the field enhancement factor and scattering intensity of the electric and toroidal dipoles, we introduce two and four nanocuboids into the nil field intensity areas in the silicon disk system, respectively. The geometric volume of the system can be increased effectively and the electric field enhancement is boosted to be 190% and 250% while the resonant wavelength of the anapole mode is almost maintained constant. The systems combined with a slot in the strongest field intensity area also follow the same law, revealing that the design strategy can be easily extended to other geometric, material and frequency systems. Different from the design strategy to add new components into the areas with strong field intensity, the incorporations occurring at the minimum intensity area is another design scheme to engineer the properties of the resonant systems and can find broad applications in nano-device designs.
由于能够在相对较大的纳米尺度体积内产生高电场增强，且具有最小吸收和非辐射特性，近年来，在高折射率介电纳米结构中激发的无偶极模式引起了广泛关注。我们提出了一种设计策略，以同时高效激发无偶极模式并保持其共振波长，这在传统介电纳米结构中一直是一个挑战。基于分析电场增强因子与电偶极子和环形偶极子散射强度之间的关系，我们分别在硅盘系统的零场强区域引入两个和四个纳米立方体。系统的几何体积可有效增加，电场增强分别提高到190%和250%，而无偶极模式的共振波长几乎保持不变。在最强场强区域结合狭缝的系统也遵循相同规律，这表明该设计策略可轻松扩展到其他几何、材料和频率系统。与在强场强区域添加新组件的设计策略不同，在最小场强区域进行的添加是另一种设计方案，用于调控共振系统的特性，并可在纳米器件设计中得到广泛应用。
