ABSTRACT
The propagation of electromagnetic waves through apertures in metal screens (or lms) has attracted considerable attention since the development of the theory of electromagnetism. Signicant interest was initially motivated by applications in radar and by understanding the penetration of conducting surfaces by electromagnetic pulses. A large number of theories with varying degrees of approximation were developed during the middle part of the twentieth century (for reviews of early work in this area, see Refs. [1-4]). In the late twentieth century, interest in this topic was reinvigorated by the increasing availability of nanofabrication tools such as focused ion beam milling and electron beam lithography and led to the rst observation of
6.1 Introduction .................................................................................................. 159 6.2 Transmission of Electromagnetic Waves through Apertures ....................... 160
6.2.1 Transmission through Circular Apertures in Thick, Perfectly Conducting Screens ........................................................... 160
6.2.2 Coaxial Apertures ............................................................................. 162 6.3 Frequency-Selective Surfaces ....................................................................... 163 6.4 Aperture Properties ...................................................................................... 166
6.4.1 Effects of Screen Conductivity ......................................................... 166 6.4.2 Effects of Aperture Size ................................................................... 167 6.4.3 Single Apertures versus Arrays of Apertures ................................... 168 6.4.4 Enhanced Optical Transmission ....................................................... 170 6.4.5 Transition from Simple Apertures to Resonant Apertures ............... 171 6.4.6 Inuence of the Substrate and Thickness of Metal .......................... 173 6.4.7 Inuence of the Optical Properties of the Aperture Filling ............. 174 6.4.8 Polarization and Angle of Incidence ................................................ 176
6.5 Resonance and Phase .................................................................................... 177 6.6 Conclusion .................................................................................................... 179 Acknowledgments .................................................................................................. 179 References .............................................................................................................. 179
“extraordinary optical transmission” (EOT) [5]. This subsequently sparked a signicant interest in understanding the propagation of visible and near-infrared light through subwavelength apertures [6,7]. Furthermore, with increasing interest in the development of optical antennas [8], it is timely to consider apertures as a category of “slot” antennas that can play a key role in a range of applications. This chapter is aimed at investigating a class of apertures that exhibit distinct localized resonances. We focus on coaxial (annular) and cross-shaped apertures and discuss the inuence of the geometry, optical properties of the lm and environment, aperture arrangement, and phase shifts on resonance.
