Guestin L, Adam A J L, Knab J R, Nagel M, Planken P C M
Delft University of Technology, Faculty of Applied Sciences, Department of Imaging Science and Technology, Optics Research Group Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Opt Express. 2009 Sep 28;17(20):17412-25. doi: 10.1364/OE.17.017412.
We have studied theoretically and experimentally the influence of a dielectric substrate on the frequency-dependent terahertz electric near-field of a small hole in a metal layer. We find that the near-field transmission spectrum and the two-dimensional field distribution of an empty hole in a thin metal layer on a substrate are almost identical to that of a hole which is also filled with the same dielectric material as the substrate. For thicker metal layers, however, the near-field spectra of filled and unfilled holes become very different. In addition, for thick metal layers, the two-dimensional field distributions are more strongly affected by the substrate, especially if we allow for an air gap between the metal and the substrate. Our results validate the -somewhat unusual- two-dimensional field distribution measured beneath a hole in a thick metal foil and highlight the effect that a substrate can have on the measurement of the near-field of an object.
我们从理论和实验两方面研究了电介质衬底对金属层中小孔的频率相关太赫兹电近场的影响。我们发现，衬底上薄金属层中空心孔的近场透射光谱和二维场分布与填充了与衬底相同电介质材料的孔几乎相同。然而，对于较厚的金属层，填充和未填充孔的近场光谱变得非常不同。此外，对于厚金属层，二维场分布受衬底的影响更大，特别是当金属和衬底之间存在气隙时。我们的结果验证了在厚金属箔下小孔下方测量的 somewhat unusual 二维场分布，并突出了衬底对物体近场测量可能产生的影响。
