Xin Jian, Zong Jie, Gao Junhua, Wang Yuxiao, Song Yinglin, Zhang Xueru
Opt Express. 2021 Jun 7;29(12):18572-18586. doi: 10.1364/OE.426746.
Metal nanorod arrays exhibit hyperbolic dispersion and optical nonlocality under certain conditions. Therefore, their optical behaviors can hardly be expressed by incident-angle-independent effective permittivity. Here we extract effective permittivity of silver nanorod arrays with diameters of 4 nm, 12 nm, and 20 nm by polarized transmission method in the visible range. The incident angles are chosen from 20° to 60° to study the influence of optical nonlocality on permittivity. We demonstrate how the diameter of the nanorods can control the effective permittivity beyond the effective medium theory. The results suggest that the effective permittivity gradually loses its accuracy as the diameter increases due to the optical nonlocality. Our experiment verifies that ultrathin nanorod arrays can resist the fluctuations caused by changes in incident angle. We also extract k-dependent effective permittivity of nanorods with larger diameters.
金属纳米棒阵列在某些条件下表现出双曲线色散和光学非局域性。因此，它们的光学行为很难用与入射角无关的有效介电常数来表示。在这里，我们通过偏振透射法在可见光范围内提取了直径为4纳米、12纳米和20纳米的银纳米棒阵列的有效介电常数。入射角从20°到60°选取，以研究光学非局域性对介电常数的影响。我们证明了纳米棒的直径如何能够超出有效介质理论来控制有效介电常数。结果表明，由于光学非局域性，随着直径的增加，有效介电常数逐渐失去其准确性。我们的实验验证了超薄纳米棒阵列能够抵抗入射角变化引起的波动。我们还提取了较大直径纳米棒的与波矢相关的有效介电常数。
