Ultrabroadband infrared near-field spectroscopy and imaging of local resonators in percolative gold films
Ultrabroadband infrared near-field spectroscopy and imaging of local resonators in percolative gold films
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DOI：
10.1364/josab.36.003315
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发表时间：
2019-12-01
影响因子：
1.9
通讯作者：
Liu, Mengkun
中科院分区：
文献类型：
--
作者：
Chen, Xinzhong;Zhang, Jiawei;Liu, Mengkun
逾渗过程在自然界中普遍存在，并导致许多关键现象，如一级相变和传染病网络。当渗透程度和组成材料的性质得到适当处理时，有效介质近似（EMA）通常可以捕获折射介质的光学性质。然而，在深亚波长制度的纳米团簇的重要的本地集体响应往往只是唯象地解决在标准的EMA形式主义。一个全面的方法，测量当地的光-物质相互作用，并注册如何影响全球光学性能的本地响应尚未建立在坚实的基础上。在本文中，我们使用红外纳米成像/光谱研究在临界逾渗阈值附近的还原性金膜。我们从实验和理论上证明了近场光谱可以定量地给出局域金团簇的特征长度尺度和它们的相对振子强度。因此，EMA分析可以与近场纳米光谱增强，以在相应的光谱范围内产生更好的远场反射光谱的可预测性。(C)2019美国光学学会
Percolation processes are ubiquitous in nature and are responsible for many critical phenomena such as first-order phase transitions and infectious epidemic networks. The optical properties of a percolative medium can generally be captured by the effective medium approximation (EMA) when the degree of percolation and the properties of the constituent materials are properly addressed. However, the important local collective responses of nanoclusters in the deep subwavelength regime are often only phenomenologically addressed in the standard EMA formalism. A comprehensive method that measures local light-matter interactions and registers how the local responses influence global optical properties has yet to be established on a firm basis. In this paper, we use infrared nanoimaging/spectroscopy to investigate percolative gold films in the vicinity of the critical percolation threshold. We demonstrate experimentally and theoretically that the near-field spectra yield quantitative information of the characteristic length scale of the local gold clusters and their relative oscillator strengths. As a result, EMA analysis can be augmented with near-field nano-spectroscopy to yield better predictability of the far-field reflection spectrumat the corresponding spectral range. (C) 2019 Optical Society of America