Resonant and nonresonant funneling through plasmonic gratings in the limit of the aperture width approaching zero

We experimentally and theoretically investigate electromagnetic funneling in thick plasmonic gratings as the aperture size approaches zero. Both resonant and nonresonant funneling mechanisms were observed to provide near unity transmission for aperture widths of similar to lambda/100. As the apertures become smaller, the resonant funneling process enters into a region of strong absorption followed by complete reflection. In sharp contrast, the broadband, nonresonant funneling mechanism continues to transmit energy at high levels for screens of <1% open area and apertures sizes as small as lambda/1500 before finally transitioning to a completely absorbing state without any abatement of the funneling into the apertures. (C) 2014 AIP Publishing LLC.