Deterministic vortices evolving frompartially coherent fields

Optical vortices—lines of zero intensity around which the field phase has a circulating or helical structure—have become important tools for many applications such as imaging, trapping, and communications. It has long been assumed, however, that there is an intrinsic conflict between optical vortices and partial coherence, in that a vortex is a deterministic phase structure, and a partially coherent field has a randomly fluctuating phase. In most cases, a vortex imposed on a partially coherent field evolves into a singularity of the two-point correlation function. We demonstrate, however, that it is possible to construct a beam that has no deterministic vortices in the source plane yet evolves such a deterministic vortex at a specified propagation distance.