Directive Emission from a Single Subwavelength Aperture in a Periodically Corrugated Silver Film

摘要

We present here an algorithm to evaluate the field in the near zone produced by a finite-size electromagnetic source in a periodic structure, referred to as the array scanning method (ASM) - FDTD method. Using a frequency-dependent silver permittivity model, obtained from measurement at optical and infrared frequencies, we implemented the corresponding modeling equations in the ASM-FDTD algorithm using the Z-transform technique. The developed algorithm is applied to the study of the enhanced radiation of a magnetic line source in a corrugated silver film, and the results indicate that the enhancement is due to the excitation of a leaky mode. We also show that other waves may be excited by the source depending on its location, and how this affects the radiation pattern.