Le Van Doan, Lefkir Yaya, Destouches Nathalie
Univ Lyon, UJM-Saint-Etienne, CNRS, Institut d'Optique Graduate School, Laboratoire Hubert Curien UMR 5516, F-42023 Saint-Etienne, France.
Nanoscale. 2023 Dec 7;15(47):19339-19350. doi: 10.1039/d3nr05569h.
Plasmonic metasurfaces made of perfectly regular 2D lattices of metallic nanoparticles deposited on surfaces or close to waveguides can exhibit hybridized plasmonic and photonic modes. The latter arise from the excitation of surface or guided modes through the in-plane coherent scattering of periodic arrays. Recently, laser-induced self-organization of random plasmonic metasurfaces has been used to create nanoparticle gratings embedded in protective layers. Despite the broad size distribution and positional disorder of nanoparticles, the resulting nanostructures exhibit strong coupling between plasmonic and photonic modes in transverse electric polarization, leading to dichroism, which is well-reproduced from one laser printing to another. Here, we examine quantitatively the effect of inhomogeneities at the nanoscale on the hybridization between localized plasmonic modes and delocalized guided modes by considering realistic laser-induced self-organized nanoparticle arrays embedded in a two-layer system. By referring to regular samples, we describe the optical mechanisms involved in the hybridization process at characteristic wavelengths, based on far and near field simulations. Two kinds of real samples are considered, featuring different levels of coupling between the plasmonic and photonic modes. The results demonstrate that controlling the statistical properties of plasmonic metasurfaces, such as the nanoparticle size distribution and average position, over areas a few micrometers wide is enough to control in a reproducible manner the hybridization mechanisms and their resulting optical properties. Thus, this study shows that the inherent irregularities of laser-induced self-organized nanostructures are compatible with smart functionalities of nanophotonics, and confirms that laser processing has huge potential for real-world applications.
由沉积在表面或靠近波导的金属纳米粒子的完美规则二维晶格制成的等离激元超表面可以展现出杂化的等离激元和光子模式。后者源于通过周期性阵列的面内相干散射对表面模式或导模的激发。最近，激光诱导的随机等离激元超表面的自组织已被用于创建嵌入保护层的纳米粒子光栅。尽管纳米粒子的尺寸分布广泛且位置无序，但所得的纳米结构在横向电极化中表现出等离激元和光子模式之间的强耦合，导致二向色性，这种二向色性在一次激光打印到另一次激光打印之间能够很好地重现。在这里，我们通过考虑嵌入双层系统中的实际激光诱导自组织纳米粒子阵列，定量研究纳米尺度上的不均匀性对局域等离激元模式和离域导模之间杂化的影响。通过参考规则样品，我们基于远场和近场模拟，描述了在特征波长下杂化过程中涉及的光学机制。考虑了两种实际样品，它们具有等离激元和光子模式之间不同程度的耦合。结果表明，在几微米宽的区域内控制等离激元超表面的统计特性，如纳米粒子尺寸分布和平均位置，足以以可重复的方式控制杂化机制及其产生的光学特性。因此，这项研究表明激光诱导自组织纳米结构的固有不规则性与纳米光子学的智能功能兼容，并证实激光加工在实际应用中具有巨大潜力。
