Continuous numerical aperture properties of a cylindrically polarized light illuminated sub-wavelength annular aperture
Journal
Optics Express
Journal Volume
17
Journal Issue
16
Pages
13646-13653
Date Issued
2009
Author(s)
Abstract
We investigated the process of focusing a radially polarized (RP) light beam through a sub-wavelength annular aperture (SAA). We found that the result was a non-diffraction doughnut-shaped light beam which propagates in free space. After analyzing the electric field component of the focus generated by the SAA structure, we identified the relationship between the focal field generated by the SAA. We then compared it to a case with a traditional objective lens. From our findings, we propose that a SAA structure can be viewed as a continuous numerical aperture optical element.
SDGs
Type
journal article