Abstract

Radially polarized beams, which possess electric field vectors arranged like the spokes of wheels pointing out from the center in the beam cross-section, have attracted much attention due to the peculiar focusing properties such as a tight focal spot size (<0.4λ) with a long depth of focus (>10λ) on the beam axis [1] when it is focused with high numerical aperture lens (NA>0.9). So far, we have clarified that the focused beam can create strong electric fields such as chain-like fields as a consequence of interaction with metal nano-structures by inducing surface plasmon modes with the longitudinal polarization [2][3]. We, here, propose a new concept to make strong electric fields with pure longitudinal polarization by using a focused radially polarized beam and a dielectric structure.

© 2015 IEEE