Siddique Radwanul Hasan, Mertens Jan, Hölscher Hendrik, Vignolini Silvia
Institute for Microstructure Technology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, Karlsruhe 76344, Germany.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
Light Sci Appl. 2017 Jul 14;6(7):e17015. doi: 10.1038/lsa.2017.15. eCollection 2017 Jul.
Subwavelength metal-dielectric plasmonic metasurfaces enable light management beyond the diffraction limit. However, a cost-effective and reliable fabrication method for such structures remains a major challenge hindering their full exploitation. Here, we propose a simple yet powerful manufacturing route for plasmonic metasurfaces based on a bottom-up approach. The fabricated metasurfaces consist of a dense distribution of randomly oriented nanoscale scatterers composed of aluminum (Al) nanohole-disk pairs, which exhibit angle-independent scattering that is tunable across the entire visible spectrum. The macroscopic response of the metasurfaces is controlled via the properties of an isolated Al nanohole-disk pair at the nanoscale. In addition, the optical field confinement at the scatterers and their random distribution of sizes result in a strongly enhanced Raman signal that enables broadly tunable excitation using a single substrate. This unique combination of a reliable and lithography-free methodology with the use of aluminum permits the exploitation of the full potential of random plasmonic metasurfaces for diagnostics and coloration.
亚波长金属-电介质等离子体超表面能够实现超越衍射极限的光管理。然而，针对此类结构的一种经济高效且可靠的制造方法仍然是阻碍其充分应用的主要挑战。在此，我们基于自下而上的方法提出了一种用于等离子体超表面的简单而强大的制造途径。所制造的超表面由由铝（Al）纳米孔-圆盘对组成的随机取向的纳米级散射体的密集分布构成，这些散射体表现出与角度无关的散射，且在整个可见光谱范围内均可调谐。超表面的宏观响应通过纳米尺度下单个Al纳米孔-圆盘对的特性来控制。此外，散射体处的光场限制及其尺寸的随机分布导致拉曼信号大幅增强，从而能够使用单个基底实现广泛可调谐的激发。这种可靠且无需光刻的方法与铝的使用的独特结合，使得能够充分挖掘随机等离子体超表面在诊断和着色方面的潜力。
