Direct generation of Bessel-like vortex beams using Pr3+ fiber laser

Abstract

Optical vortex beams carry a ring spatial form and an orbital angular momentum (OAM) assigned by a topological charge ℓ [1], and they have been widely studied in a variety of applications, such as optical tweezers [2], microscopic imaging [3] and material processing [4]. The above mentioned applications strongly require compact and robust visible vortex sources with high efficiency.