title: Focusing radially polarized light by a concentrically corrugated silver film without a hole.
abstract: We report a phenomenon of focusing a radially polarized beam from the visible range by a silver film with no hole on the optical axis and double-sided concentric corrugations. The axes of symmetry of grooves and the illuminating beam coincide. An Ag lens of 100 nm thickness, five grooves, of which the outermost has 5 microm diameter, at lambda=400 nm transmits 22% of electric energy and focuses light into a 0.2lambda2 spot area at a focal length close to 2lambda, while at lambda=500 nm the results are 11%, 0.16lambda2 and lambda, respectively. This Ag lens focuses without contribution of evanescent waves a far-field source into a far-field spot. The nanolens acts like a refractive optical system of high numerical aperture close to unity.
authors.affiliation: Faculty of Physics, University of Warsaw, Pasteura 7, 02-093 Warsaw, Poland. piotr.wrobel@igf.fuw.edu.pl
authors.forename: Piotr
authors.initials: P
authors.lastname: Wróbel
authors.forename: Jacek
authors.initials: J
authors.lastname: Pniewski
authors.forename: Tomasz J
authors.initials: TJ
authors.lastname: Antosiewicz
authors.forename: Tomasz
authors.initials: T
authors.lastname: Szoplik