Abstract
In this letter, the problem of extraordinary (ET) transmission of electromagnetic waves through opaque screens perforated with subwave-length holes is addressed from an analytical point of view. Our purpose was to find a closed-form expression for the transmission coefficient in a simple case in order to explore and clarify, as much as possible, the physical background of the phenomenon. The solution of this canonical example, apart from matching quite well with numerical simulations given by commercial solvers, has provided new insight in extraordinary transmission as well as Wood's anomaly. Thus, our analysis has revealed that one of the key factors behind ET is the continuous increase of excess electric energy around the holes as the frequency approaches the onset of some of the higher-order modes associated with the periodicity of the screen. The same analysis also helps to clarify the role of surface modes -or spoof plasmons- in the onset of ET.
Highlights
A few years ago Ebbesen et al [1] reported a phenomenon of extraordinary transmission (ET) through metallic screens periodically perforated with sub-wavelength holes
This physical effect was originally attributed to the excitation of surface plasmons on the diffraction screen [3, 4, 5], in apparent contradiction with Bethe’s theory for small apertures [2]
ET has been observed at millimeter wave frequencies [6], when metals can no longer be considered solid plasmas
Summary
A few years ago Ebbesen et al [1] reported a phenomenon of extraordinary transmission (ET) through metallic screens periodically perforated with sub-wavelength holes. W. Ebbesen, “Theory of extraordinary optical transmission through subwavelength hole arrays,” Phys. J. Garcıa-Vidal, “Enhanced millimeter-wave transmission through subwavelength hole arrays,” Opt. Lett.
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