Petronella Francesca, Madeleine Tristan, De Mei Vincenzo, Zaccagnini Federica, Striccoli Marinella, D'Alessandro Giampaolo, Rumi Mariacristina, Slagle Jonathan, Kaczmarek Malgosia, De Sio Luciano
National Research Council of Italy, Institute of Crystallography, CNR-IC, Rome Division, Area della Ricerca Roma 1 Strada Provinciale 35d, n. 9, 00010 Montelibretti (RM), Italy.
School of Mathematical Science, University of Southampton, Southampton SO17 1BJ, United Kingdom.
ACS Appl Mater Interfaces. 2023 Oct 25;15(42):49468-49477. doi: 10.1021/acsami.3c09896. Epub 2023 Oct 10.
Metasurfaces can be realized by organizing subwavelength elements (e.g., plasmonic nanoparticles) on a reflective surface covered with a dielectric layer. Such an array of resonators, acting collectively, can completely absorb the resulting resonant wavelength. Unfortunately, despite the excellent optical properties of metasurfaces, they lack the tunability to perform as adaptive optical components. To boost the utilization of metasurfaces and realize a new generation of dynamically controlled optical components, we report our recent finding based on the powerful combination of an innovative metasurface-optical absorber and nematic liquid crystals (NLCs). The metasurface consists of self-assembled silver nanocubes (AgNCs) immobilized on a 50 nm thick gold layer by using a polyelectrolyte multilayer as a dielectric spacer. The resulting optical absorbers show a well-defined reflection band centered in the near-infrared of the electromagnetic spectrum (750-770 nm), a very high absorption efficiency (∼60%) at the resonant wavelength, and an elevated photothermal efficiency estimated from the time constant value (34 s). Such a metasurface-based optical absorber, combined with an NLC layer, planarly aligned via a photoaligned top cover glass substrate, shows homogeneous NLC alignment and an absorption band photothermally tunable over approximately 46 nm. Detailed thermographic studies and spectroscopic investigations highlight the extraordinary capability of the active metasurface to be used as a light-controllable optical absorber.
超表面可以通过在覆盖有介电层的反射表面上组织亚波长元件（例如，等离子体纳米颗粒）来实现。这样一组共同作用的谐振器可以完全吸收产生的谐振波长。不幸的是，尽管超表面具有出色的光学特性，但它们缺乏作为自适应光学元件的可调谐性。为了提高超表面的利用率并实现新一代动态控制的光学元件，我们基于创新的超表面光学吸收器和向列型液晶（NLC）的强大组合报告了我们最近的发现。该超表面由通过使用聚电解质多层作为介电间隔层固定在50nm厚金层上的自组装银纳米立方体（AgNC）组成。所得的光学吸收器在电磁光谱的近红外区域（750 - 770nm）有一个明确的反射带，在谐振波长处具有非常高的吸收效率（约60%），并且根据时间常数估计具有较高的光热效率（34s）。这种基于超表面的光学吸收器与通过光取向顶盖玻璃基板平面取向的NLC层相结合，显示出均匀的NLC取向，并且吸收带可通过光热调节约46nm。详细的热成像研究和光谱研究突出了有源超表面作为光控光学吸收器的非凡能力。
