Mao Peng, Liu Changxu, Niu Yubiao, Qin Yuyuan, Song Fengqi, Han Min, Palmer Richard E, Maier Stefan A, Zhang Shuang
School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.
Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig Maximilians University of Munich, 80539, Munich, Germany.
Adv Mater. 2021 Jun;33(23):e2007623. doi: 10.1002/adma.202007623. Epub 2021 Apr 30.
Materials show various responses to incident light, owing to their unique dielectric functions. A well-known example is the distinct colors displayed by metals, providing probably the simplest method to identify gold, silver, and bronze since ancient times. With the advancement of nanotechnology, optical structures with feature sizes smaller than the optical wavelength have been routinely achieved. In this regime, the optical response is also determined by the geometry of the nanostructures, inspiring flourishing progress in plasmonics, photonic crystals, and metamaterials. Nevertheless, the nature of the materials still plays a decisive role in light-matter interactions, and this material-dependent optical response is widely accepted as a norm in nanophotonics. Here, a counterintuitive system-plasmonic nanostructures composed of different materials but exhibiting almost identical reflection-is proposed and realized. The geometric disorder embedded in the system overwhelms the contribution of the material properties to the electrodynamics. Both numerical simulations and experimental results provide concrete evidence of the insensitivity of the optical response to different plasmonic materials. The same optical response is preserved with various materials, providing great flexibility of freedom in material selection. As a result, the proposed configuration may shed light on novel applications ranging from Raman spectroscopy, photocatalysis, to nonlinear optics.
由于材料具有独特的介电函数，它们对入射光表现出各种响应。一个众所周知的例子是金属呈现出的独特颜色，这可能是自古以来识别金、银和青铜最简单的方法。随着纳米技术的发展，特征尺寸小于光波长的光学结构已常规实现。在这种情况下，光学响应也由纳米结构的几何形状决定，这激发了等离子体学、光子晶体和超材料的蓬勃发展。然而，材料的性质在光与物质的相互作用中仍然起着决定性作用，这种依赖于材料的光学响应在纳米光子学中被广泛视为一种常态。在此，提出并实现了一种违反直觉的系统——由不同材料组成但表现出几乎相同反射的等离子体纳米结构。系统中嵌入的几何无序压倒了材料特性对电动力学的贡献。数值模拟和实验结果都为光学响应对不同等离子体材料不敏感提供了具体证据。各种材料都保持相同的光学响应，这在材料选择上提供了极大的自由度。因此，所提出的结构可能为从拉曼光谱、光催化到非线性光学等新型应用带来启示。
