Extraordinary THz transmission with a small beam spot: the leaky wave mechanism

Abstract

This is the peer reviewed version of the following article: M. Navarro-Cía, V. Pacheco-Peña, S. A. Kuznetsov, M. Beruete: Extraordinary THz Transmission with a Small Beam Spot: The Leaky Wave Mechanism. Advanced Optical Materials 2018, 1701312, which has been published in final form at https://doi.org/10.1002/adom.201701312. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. ; The discovery of extraordinary optical transmission (EOT) through patterned metallic foils in the late 1990s was decisive for the development of plasmonics and cleared the path to employ small apertures for a variety of interesting applications all along the electromagnetic spectrum. However, a typical drawback often found in practical EOT structures is the large size needed to obtain high transmittance peaks. Consequently, practical EOT arrays are usually illuminated using an expanded (mimicking a plane wave) beam. Here, it is shown with numerical and experimental results in the THz range that high transmittance peaks can be obtained even with a reduced illumination spot exciting a small number of holes, provided that the structure has a sufficient number of lateral holes out of the illumination spot. These results shed more light on the prominent role of leaky waves in the underlying physics of EOT and have a direct impact on potential applications. ; This work was partially supported by the Spanish Ministerio de Economía y Competitividad with European Union Fondo Europeo de Desarrollo Regional (FEDER) funds [TEC2014-51902-C2-2-R]. M.N.-C. acknowledges support from University of Birmingham [Birmingham Fellowship]. V.P.-P. was sponsored by Spanish Ministerio de Educación, Cultura y Deporte [formación de profesorado universitario (FPU) AP-2012-3796]. S.A.K. acknowledges support from the Novosibirsk State University (NSU) program 5-100 established by the Russian Ministry of Education and Science.