Nanostructured gold films as broadband terahertz antireflection coatings

被引：150

作者：

Thoman, Andreas ^{[1
]}

Kern, Andreas ^{[1
]}

Helm, Hanspeter ^{[1
]}

Walther, Markus ^{[1
]}

机构：

[1] Univ Freiburg, Freiburg Mat Res Ctr, D-79104 Freiburg, Germany

来源：

PHYSICAL REVIEW B | 2008年 / 77卷 / 19期

关键词：

D O I：

10.1103/PhysRevB.77.195405

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

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.

引用

页数：9