Graduate School of Engineering and ‡Photonics Advanced Research Center, Osaka University , 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Nano Lett. 2016 May 11;16(5):3166-72. doi: 10.1021/acs.nanolett.6b00500. Epub 2016 Apr 25.
Metallic nanostructures can be designed to effectively reflect different colors at deep-subwavelength scales. Such color manipulation is attractive for applications such as subwavelength color printing; however, challenges remain in creating saturated colors with a general and intuitive design rule. Here, we propose a simple design approach based on all-aluminum gap-plasmonic nanoantennas, which is capable of designing colors using knowledge of the optical properties of the individual antennas. We demonstrate that the individual-antenna properties that feature strong light absorption at two distinct frequencies can be encoded into a single subwavelength-pixel, enabling the creation of saturated colors, as well as a dark color in reflection, at the optical diffraction limit. The suitability of the designed color pixels for subwavelength printing applications is demonstrated by showing microscopic letters in color, the incident polarization and angle insensitivity, and color durability. Coupled with the low cost and long-term stability of aluminum, the proposed design strategy could be useful in creating microscale images for security purposes, high-density optical data storage, and nanoscale optical elements.
金属纳米结构可以被设计成在深亚波长尺度上有效地反射不同的颜色。这种颜色操控对于亚波长彩色印刷等应用很有吸引力；然而，在创建具有通用和直观设计规则的饱和颜色方面仍然存在挑战。在这里，我们提出了一种基于全铝间隙等离子体纳米天线的简单设计方法，该方法可以利用单个天线的光学特性知识来设计颜色。我们证明，在两个不同频率下具有强光吸收特性的单个天线特性可以被编码到单个亚波长像素中，从而在光学衍射极限处实现饱和颜色以及反射中的暗颜色。通过显示彩色微观字母、入射偏振和角度不敏感性以及颜色耐久性，证明了设计的彩色像素在亚波长印刷应用中的适用性。结合铝的低成本和长期稳定性，所提出的设计策略可用于创建用于安全目的、高密度光数据存储和纳米光学元件的微尺度图像。
