Extraordinary optical transmission

Extraordinary optical transmission (EOT) is an opticalphenomenon that happens in slits that are narrower than the wavelength of the light [Ebbesen, T. W.; Ghaemi, H. F.; Thio, Tineke; Grupp, D. E.; Lezec, H. J, "Extraordinary Optical Transmission through Sub-wavelength Hole Arrays", APS 1998, http://adsabs.harvard.edu/abs/1998APS..MAR.S1511E] . Generally when light falls on such a slit, it emerges having been diffracted isotropically, ie it scatters in all directions evenly. However, if instead the slit is surrounded by highly patterned grooves, a highly directional beam emerges instead of the diffracted & isotropic beam. This is called an Extraordinary Optical Transmission.

This phenomenon is attributed to the presence of surface plasmon resonances [M. Mrejen, A. Israel, H. Taha, M. Palchan, and A. Lewis, "Near-field characterization of extraordinary optical transmission in sub-wavelength aperture arrays," Opt. Express 15, 9129-9138 (2007)http://www.opticsinfobase.org/abstract.cfm?URI=oe-15-15-9129] and constructive interference. A surface plasmon (SP) is a collective excitation of the electrons at the junction between a conductor and an insulator and is one of a series of interactions between light and a metal surface called Plasmonics.

Currently, there is experimental evidence of EOT out of the optical range [M. Beruete, M. Sorolla, I. Campillo, J.S. Dolado, L. Martín-Moreno, J. Bravo-Abad, and F. J. García-Vidal, “Enhanced Millimeter Wave Transmission Through Quasioptical Subwavelength Perforated Plates”, IEEE Trans. Antennas and Propagation, Vol. 53, No. 6, pp. 1897-1903, June 2005.] . Analytical approaches also predict EOT on perforated plates with a perfect conductor model [C.C. Chen, "Transmission through a Conducting Screen Perforated Periodically with Apertures", IEEE Trans. Microw. Theory and Tech., Vol. 18, No. 9, pp. 627-632, Sep. 1970. L. Martín-Moreno, F. J. García-Vidal, H. J. Lezec, K. M. Pellerin, T. Thio, J. B. Pendry, and T.W. Ebbesen, “Theory of Extraordinary Optical Transmission through Subwavelength Hole Arrays”, Phys. Rev. Lett., Vol. 86, pp. 1114-1117, (2001). F. J. Garcia de Abajo, R. Gomez-Medina, and J. J. Saenz, “Full transmission through perfect-conductor subwavelength hole arrays,” Phys. Rev. E, Vol. 72, pp. 016608-1-4, (2005).] . Holes can somewhat emulate plasmons at other regions of the Electromagnetic spectrum where they do not exist [ R. Ulrich and M. Tacke, “Submillimeter waveguidingon periodic metal structure,” Appl. Phys. Lett., Vol. 22, pp. 251 – 253, 1972. J. B. Pendry, L. Martín-Moreno, and F. J. García-Vidal, “Mimicking surface plasmons with structured surfaces,” Science, Vol. 305, pp. 847 - 848, 6 August 2004.F. J. Garcia de Abajo and J. J. Saenz “Electromagnetic surface modes in structured perfect-conductor surfaces,” Phys. Rev. Lett., Vol. 95, pp. 233901-1-4 (2005)] . 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.

Simple analytical explanations of this phenomenon have been elaborated, emphasizing the similarity between arrays of particlesand arrays of holes, and establishing that the phenomenon is dominated by diffraction [F. J. García de Abajo, “Light scattering by particle and hole arrays,” Reviews of Modern Physics, Vol. 79, p. 1267 - 1290, 10 October 2007.]

Applications

EOT is expected to play an important role in the creation of components of 'photonic' circuits. (Photonic circuits are analogous to electronic circuits.)

One of the most ground-breaking results linked to EOT is the possibility to implement a Left-Handed Metamaterial (LHM) by simply stacking hole arrays, as demonstrated in [M. Beruete, M. Sorolla, and I. Campillo,”Left-Handed Extraordinary Optical Transmission through a Photonic Crystal of Subwavelength Hole Arrays”, Optics Express, Vol. 14, No. 12, pp. 5445-5455, (12 June 2006). http://www.opticsexpress.org/abstract.cfm?id=90303.]

References