Extraordinary THz Transmission with a Small Beam Spot: The Leaky Wave Mechanism

摘要

The discovery of extraordinary optical transmission (EOT) through patternedrnmetallic foils in the late 1990s was decisive for the development of plasmonicsrnand cleared the path to employ small apertures for a variety of interestingrnapplications all along the electromagnetic spectrum. However, a typicalrndrawback often found in practical EOT structures is the large size needed tornobtain high transmittance peaks. Consequently, practical EOT arrays are usuallyrnilluminated using an expanded (mimicking a plane wave) beam. Here, itrnis shown with numerical and experimental results in the THz range that highrntransmittance peaks can be obtained even with a reduced illumination spotrnexciting a small number of holes, provided that the structure has a sufficientrnnumber of lateral holes out of the illumination spot. These results shed morernlight on the prominent role of leaky waves in the underlying physics of EOTrnand have a direct impact on potential applications.