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 diameter, at transmits 22% of electric energy and focuses light into a spot area at a focal length close to , while at the results are 11%, and , 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.
- Received 15 December 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.183902
©2009 American Physical Society