Evanescently coupled resonance in surface plasmon enhanced transmission

A. Krishnan, T. Thio, T. J. Kim, H. J. Lezec, T. W. Ebbesen, P. A. Wolff, J.B. Pendry, L. Martin-Moreno, F. J. Garcia-Vidal

Abstract:

The optical transmission through subwavelength holes in metal films can be enhanced by several orders of magnitude by enabling interaction of the incident light with independent surface plasmon modes on either side of the film. Here we show that this transmission is boosted by an additional factor of ~10 when the energies of the surface plasmon modes on both sides are matched. These results, confirmed by a three-dimensional theoretical analysis, give a totally new understanding of the phenomenon of surface plasmon enhanced transmission. It is found that the holes behave like subwavelength Fabry-Perot resonators for the evanescent waves coupling the surface plasmons on either side of the film. In this unusual device, the reflection at either end of the cavity is provided by the surface plasmon modes which act as frequency dependent mirrors.

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last updated Weds 19 June13:49 BST 2002 by JBP