Visualizing polarization singularities in Bessel-Poincaré beams

• Published in: Optics express Vol. 23; no. 9; pp. 12444 - 12453
• Main Authors: Shvedov, V, Karpinski, P, Sheng, Y, Chen, X, Zhu, W, Krolikowski, W, Hnatovsky, C
• Format: Journal Article
• Language: English
• Published: United States 04.05.2015
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.23.012444

We demonstrate that an annulus of light whose polarization is linear at each point, but the plane of polarization gradually rotates by π radians can be used to generate Bessel-Poincaré beams. In any transverse plane this beam exhibits concentric rings of polarization singularities in the form of L-lines, where the polarization is purely linear. Although the L-lines are invisible in terms of light intensity variations, we present a simple way to visualize them as dark rings around a sharp peak of intensity in the beam center. To do this we use a segmented polarizer whose transmission axes are oriented differently in each segment. The radius of the first L-line is always smaller than the radius of the central disk of the zero-order Bessel beam that would be produced if the annulus were homogeneously polarized and had no phase circulation along it.