Extraordinary optical transmission

Extraordinary optical transmission (EOT) is the phenomenon of greatly enhanced transmission of light through a <a href="/facts/Subwavelength/kcJU0ymz">subwavelength</a> aperture in an otherwise opaque metallic film which has been patterned with a regularly repeating periodic structure. Generally when <a href="/facts/Light/jeofpMn4">light</a> of a certain <a href="/facts/Wavelength/kcJU0ymz">wavelength</a> falls on a subwavelength aperture, it is <a href="/facts/Diffraction/Mk80xXHT">diffracted</a> <a href="/facts/Isotropy/mc3QEY2x">isotropically</a> in all directions evenly, with minimal <a href="/facts/Far-field/wS2Dp5lv">far-field</a> transmission. This is the understanding from classical aperture theory as described by <a href="/facts/Hans_Bethe/X6bkxRRI">Bethe</a>. In EOT however, the regularly repeating structure enables much higher transmission efficiency to occur, up to several orders of magnitude greater than that predicted by classical aperture theory. It was first described in 1998.
This phenomenon that was fully analyzed with a microscopic scattering model is partly attributed to the presence of <a href="/facts/Surface_plasmon/6H6a2fYC">surface plasmon</a> resonances and <a href="/facts/Constructive_interference/lI5f78I4">constructive interference</a>. A surface plasmon (SP) is a collective excitation of the <a href="/facts/Electron/L0KBo5cW">electrons</a> at the junction between a <a href="/facts/Electrical_conductor/BSuyupLP">conductor</a> and an <a href="/facts/Electrical_insulation/SfSXkrh5">insulator</a> and is one of a series of interactions between light and a metal surface called <a href="/facts/Plasmonics/IAR0rUhe">Plasmonics</a>.
Currently, there is experimental evidence of EOT out of the optical range. Analytical approaches also predict EOT on perforated plates with a <a href="/facts/Perfect_conductor/nUnW4gMw">perfect conductor</a> model. Holes can somewhat emulate <a href="/facts/Plasmons/kuCMxx5f">plasmons</a> at other regions of the <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a> where they do not exist. Then, the plasmonic contribution is a very particular peculiarity of the EOT resonance and should not be taken as the main contribution to the phenomenon. More recent work has shown a strong contribution from overlapping <a href="/facts/Evanescent_wave_coupling/svCyRKr7">evanescent wave coupling</a>, which explains why <a href="/facts/Surface_plasmon_resonance/8JKldMUT">surface plasmon resonance</a> enhances the EOT effect on both sides of a metallic film at optical frequencies, but accounts for the terahertz-range transmission.
Simple analytical explanations of this phenomenon have been elaborated, emphasizing the similarity between arrays of particles and arrays of holes, and establishing that the phenomenon is dominated by <a href="/facts/Diffraction/Mk80xXHT">diffraction</a>.

Extraordinary optical transmission open-in-new

Extraordinary optical transmission