title: Visualizing polarization singularities in Bessel-Poincaré beams.
abstract: 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.
authors.forename: V
authors.initials: V
authors.lastname: Shvedov
authors.forename: P
authors.initials: P
authors.lastname: Karpinski
authors.forename: Y
authors.initials: Y
authors.lastname: Sheng
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: W
authors.initials: W
authors.lastname: Zhu
authors.forename: W
authors.initials: W
authors.lastname: Krolikowski
authors.forename: C
authors.initials: C
authors.lastname: Hnatovsky