Interplay of Kerr and Raman beam cleaning with a multimode microstructure fiber

We experimentally study the competition between Kerr
beam self-cleaning and Raman beam cleanup in a multimode
air–silica microstructure optical fiber. Kerr beam
self-cleaning of the pump is observed for a certain range
of input powers only. Stokes Raman beam generation
and cleanup lead to both depletion and degradation of
beam quality for the pump. The interplay of modal four wave
mixing and Raman scattering in the infrared domain
leads to the generation of a multimode supercontinuum
ranging from 500 nm up to 1800 nm.