Nanostructured gold films as broadband terahertz antireflection coatings
Nanostructured gold films as broadband terahertz antireflection coatings
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DOI：
10.1103/physrevb.77.195405
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发表时间：
2008-05-01
影响因子：
3.7
通讯作者：
Walther, Markus
中科院分区：
文献类型：
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作者：
Thoman, Andreas;Kern, Andreas;Walther, Markus
在太赫兹频率范围内，纳米厚的随机纳米结构金膜作为非色散基底的宽带波阻抗匹配涂层的潜力得到了证明。基于波阻抗方法以及我们所研究薄膜的特定非德鲁德电导率，我们对硅和空气之间镀膜界面的反射率进行了建模，并表明纳米结构薄膜比传统的块状金属层具有更好的宽带性能。在0.2 - 2.2太赫兹频率范围内通过太赫兹时域光谱对不同金纳米结构进行的实验研究验证了理论模型的预测。对先前开发的用于时域有限差分法的子网格划分方案的扩展，使我们能够模拟太赫兹脉冲在未镀膜和镀膜样品中的传播，并在以亚纳米精度改变薄膜厚度时追踪内部反射脉冲的衰减和整形。
The potential of nanometer-thick, randomly nanostructured gold films as broadband wave impedance-matching coatings for nondispersive substrates in the terahertz frequency range is demonstrated. Based on a wave impedance approach and the specific non-Drude conductivity of our films, we model the reflectivity at the coated inter-face between silicon and air and show that nanostructured films offer a considerably better broadband performance than conventional bulk metallic layers. The predictions from the theoretical model are verified in experimental studies of different gold nanostructures investigated by terahertz time-domain spectroscopy in the frequency range of 0.2-2.2 THz. An extension of a previously developed subgridding scheme for the finite-difference time-domain method allows us to simulate terahertz-pulse propagation through uncoated and coated samples and to follow attenuation and reshaping of the internally reflected pulse when the film thickness is varied with subnanometer precision.