Plasmonic Bragg reflectors for enhanced extraordinary optical transmission through nano-hole arrays in a gold film

We demonstrate the use of plasmonic Bragg reflectors (PBRs) to enhance the extraordinary optical transmission (EOT) from an array of sub-wavelength apertures in a gold film. Arrays of partially milled lines and dimples are placed at the edges of an array of nano-holes in a gold film. These PBR structures, with half the pitch of the array, capture light scattered away from the array by Bragg reflection. By appropriate positioning of the PBR, the light is reflected in-phase with the EOT light and thereby doubles the EOT without shifting the wavelength of the resonant transmission peak. Furthermore, the PBR structures show strong polarization dependence that is also strongly dependent on the structure of the PBR, as explained in terms of scattering of the surface waves. (c) 2007 Optical Society of America.