Robustly Efficient Superfocusing of Immersion Plasmonic Lenses Based on Coupled Nanoslits

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• 作者：Yechuan Zhu ; Weizheng Yuan ; Yiting Yu ; Ping Wang
• 关键词：Plasmonic lenses ; Metallic nanostructures ; Superfocusing
• 刊名：Plasmonics
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：11
• 期：6
• 页码：1543-1548
• 全文大小：1,746 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Biotechnology
  Nanotechnology
  Biophysics and Biomedical Physics
  Biochemistry
  
• 出版者：Springer US
• ISSN：1557-1963
• 卷排序：11

文摘

We report plasmonic lenses consisting of coupled nanoslits immersed in a high-index medium to obtain the robustly efficient superfocusing. Based on the geometrical optics and the wavefront reconstruction theory, an array of nanoslits perforated in a gold film and a series of spacings between adjacent nanoslits are optimally designed to realize the desired phase modulation for light focusing. The numerical results verify the design of each plasmonic lens in excellent agreement. For the given total phase difference of 2π, the immersion plasmonic lenses with smaller lens aperture can have much better focusing performance than the non-immersion one. A superfocusing spot of λ/4.39 is achieved using an oil immersion plasmonic lens with an aperture size of 4.97λ, resulting in a resolution improvement of 68.9 % compared with the non-immersion lens. Moreover, such superfocusing performance can be still well kept when the structural parameters of the lens, e.g., nanoslit width and metal film thickness, are deviated from the original design, making the final implementation of the superfocusing lenses much easier.