title: Determination of topological charges of polychromatic optical vortices.
abstract: We introduce a simple, single beam method for determination of the topological charge of polychromatic optical vortices. It is based on astigmatic transformation of singular optical beams, where the intensity pattern of a vortex beam acquires a form of dark stripes in the focal plane of a cylindrical lens. The number of the dark stripes is equal to the modulus of the vortex topological charge, while the stripe tilt indicates the charge sign. We demonstrate experimentally the effectiveness of this technique by revealing complex topological structure of polychromatic singular beams.
authors.affiliation: Nonlinear Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200, Australia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Denisenko
authors.forename: Vladlen
authors.initials: V
authors.lastname: Shvedov
authors.forename: Anton S
authors.initials: AS
authors.lastname: Desyatnikov
authors.forename: Dragomir N
authors.initials: DN
authors.lastname: Neshev
authors.forename: Wieslaw
authors.initials: W
authors.lastname: Krolikowski
authors.forename: Alexander
authors.initials: A
authors.lastname: Volyar
authors.forename: Marat
authors.initials: M
authors.lastname: Soskin
authors.forename: Yuri S
authors.initials: YS
authors.lastname: Kivshar
mesh_terms: D003116:Color; D003198:Computer Simulation; D008027:Light; D008962:Models, Theoretical; D012031:Refractometry / Q000379:methods*; D012542:Scattering, Radiation