Chen Yang, Yang Xiaodong, Gao Jie
Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO 65409 USA.
Light Sci Appl. 2019 May 15;8:45. doi: 10.1038/s41377-019-0156-8. eCollection 2019.
Helical structures have attracted considerable attention due to their inherent optical chirality. Here, we report a unique type of 3D Janus plasmonic helical nanoaperture with direction-controlled polarization sensitivity, which is simply fabricated via the one-step grayscale focused ion beam milling method. Circular dichroism in transmission of as large as 0.72 is experimentally realized in the forward direction due to the spin-dependent mode coupling process inside the helical nanoaperture. However, in the backward direction, the nanoaperture acquires giant linear dichroism in transmission of up to 0.87. By encoding the Janus metasurface with the two nanoaperture enantiomers having specified rotation angles, direction-controlled polarization-encrypted data storage is demonstrated for the first time, where a binary quick-response code image is displayed in the forward direction under the circularly polarized incidence of a specified handedness, while a distinct grayscale image is revealed in the backward direction under linearly polarized illumination with a specified azimuthal angle. We envision that the proposed Janus helical nanoapertures will provide an appealing platform for a variety of applications, which will range from multifunctional polarization control, enantiomer sensing, data encryption and decryption to optical information processing.
螺旋结构因其固有的光学手性而备受关注。在此，我们报道了一种独特的三维双面等离子体螺旋纳米孔，其具有方向可控的偏振敏感性，通过一步灰度聚焦离子束铣削方法即可简单制备。由于螺旋纳米孔内部的自旋相关模式耦合过程，在正向实验实现了高达0.72的透射圆二色性。然而，在反向，纳米孔在透射中获得了高达0.87的巨大线性二色性。通过用具有特定旋转角度的两种纳米孔对映体对双面超表面进行编码，首次展示了方向可控的偏振加密数据存储，即在特定手性的圆偏振入射下，正向显示二进制快速响应码图像，而在具有特定方位角的线偏振照明下，反向显示清晰的灰度图像。我们设想，所提出的双面螺旋纳米孔将为各种应用提供一个有吸引力的平台，这些应用将涵盖从多功能偏振控制、对映体传感、数据加密和解密到光学信息处理等领域。
