Vortex array carried by a pseudo-nondiffracting beam

A method for generation of an array of optical vortices nested at off-axis positions in a pseudonondiffracting background beam is proposed. The free-space propagation of a single off-axis vortex is analyzed thoroughly. Particular attention is focused on evolution of the beam intensity profile, description of the trajectory of the original off-axis vortex, and nucleation of additional pairs of vortices. Conditions that provide propagation stability are also discussed. An experimental setup for generation of a pseudo-nondiffracting off-axis vortex beam and an array of off-axis vortices is proposed. (C) 2004 Optical Society of America.