Nonresonant broadband funneling of light via ultrasubwavelength channels

Enhancing and funneling light efficiently through deep subwavelength apertures is essential in harnessing light-matter interaction. Thus far, this has been accomplished resonantly, by exciting the structural surface plasmons of perforated nanostructured metal films, a phenomenon known as extraordinary optical transmission. Here, we present a new paradigm structure which possesses all the capabilities of extraordinary optical transmission platforms, yet operates nonresonantly on a distinctly different mechanism. Our proposed platform demonstrates efficient ultrabroadband funneling of optical power confined in an area as small as ∼(λ500)2, where optical fields are enhanced, thus exhibiting functional possibilities beyond resonant platforms. We analyze the nonresonant mechanism underpinning such a phenomenon with a simple quasistatic picture, which shows excellent agreement with our numerical simulations. © 2011 American Physical Society.