Propagation dynamics of phase dislocations embedded in a Bessel light beam

The evolution of an off-axis optical vortex inserted in a propagation invariant J(0) Bessel background beam is studied in a linear medium. Good coincidence of the measured intensity distributions with simulations allows us to derive the phase distribution and topology of the beam. The initial vortex interacts with the edge dislocations of the background beam to form a propagating mixed edge-screw dislocation. Finally we observe the trapping of a stable vortex in the center of the beam. The simple wave vector distribution of the Bessel background beam allows for an interpretation of the propagation dynamics of the dislocations. (C) 2002 Elsevier Science B.V. All rights reserved.