Nanostructured gold films as broadband terahertz antireflection coatings
- 6 May 2008
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 77 (19), 195405
- https://doi.org/10.1103/physrevb.77.195405
Abstract
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 interface 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 . 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.
Keywords
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