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Subdiffraction light focusing on a grating substrate.

Research paper by Anne A Sentenac, Patrick C PC Chaumet

Indexed on: 04 Sep '08Published on: 04 Sep '08Published in: Physical review letters



Abstract

We describe a way to generate subdiffraction light spots that can be moved over a surface without resorting to near-field manipulation, nonlinear effects, or negative index materials. We use a periodically patterned substrate that converted efficiently, through scattering, the impinging propagative waves into evanescent ones. Then we optimize the wave front of the incident propagative beam so that the grating-scattered evanescent waves interfere constructively at the focal point. Numerical simulations show that focus spots as small as one-sixth of a wavelength can be obtained at any point on the substrate. One foreseen application is high resolution surface imaging.