Yao Jin, Hsu Wei-Lun, Liang Yao, Lin Rong, Chen Mu Ku, Tsai Din Ping
Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
Department of Optics and Photonics, National Central University, Taoyuan 320371, Taiwan.
Sci Adv. 2024 Apr 19;10(16):eadn2752. doi: 10.1126/sciadv.adn2752. Epub 2024 Apr 17.
Nonlocal effects originating from interactions between neighboring meta-atoms introduce additional degrees of freedom for peculiar characteristics of metadevices, such as enhancement, selectivity, and spatial modulation. However, they are generally difficult to manipulate because of the collective responses of multiple meta-atoms. Here, we experimentally demonstrate the nonlocal metasurface to realize the spatial modulation of dark-field emission. Plasmonic asymmetric split rings (ASRs) are designed to simultaneously excite local dipole resonance and nonlocal quasi-bound states in the continuum and spatially extended modes. With one type of unit, nonlocal effects are tailored by varying array periods. ASRs at the metasurface's edge lack sufficient interactions, resulting in stronger dark-field scattering and thus edge emission properties of the metasurface. Pixel-level spatial control is demonstrated by simply erasing some units, providing more flexibility than conventional local metasurfaces. This work paves the way for manipulating nonlocal effects and facilitates applications in optical trapping and sorting at the nanoscale.
相邻元原子之间的相互作用产生的非局域效应为超构器件的特殊特性引入了额外的自由度，如增强、选择性和空间调制。然而，由于多个元原子的集体响应，它们通常难以操控。在此，我们通过实验证明了非局域超表面可实现暗场发射的空间调制。等离子体非对称分裂环（ASR）被设计用于同时激发局部偶极子共振以及连续谱中的非局域准束缚态和空间扩展模式。使用一种单元类型，通过改变阵列周期来调整非局域效应。超表面边缘处的ASR缺乏足够的相互作用，导致更强的暗场散射，进而形成超表面的边缘发射特性。通过简单擦除一些单元展示了像素级空间控制，这比传统的局部超表面提供了更大的灵活性。这项工作为操控非局域效应铺平了道路，并促进了其在纳米尺度的光学捕获和分选方面的应用。
