Spatial self-cleaning of laser beams with arbitrary state of polarization of light

We report on an extensive experimental study of the state of polarization of light during spatial beam self-cleaning in graded-index multimode fibers. Our results show that, depending on the experimental conditions, intense multimode beams with a bell-shape intensity profile can be obtained at the fiber output with a degree of polarization which ranges from a few percents to about 100%. These results extend the range of applications of the beam self-cleaning effect and provide novel useful insight for the understanding of the physical mechanisms behind the beam self-cleaning effect.