Mode Decomposition Method for Investigating the Nonlinear Dynamics of a Multimode Beam

We overview our recent experimental studies on the nonlinear spatial reshaping of multimode beams at the output of multimode optical fibers. We use a holographic mode decomposition technique, which permits to reveal the variation of the spatial mode composition at the fiber output, as determined by either conservative (the Kerr effect) or dissipative (Raman scattering) nonlinear processes. For the first case, we consider the effect of spatial beam self-cleaning, and we compare experimental mode decompositions with predictions based on the thermodynamic theory, including the case of beams carrying nozero orbital angular momentum. For the second case, we analyze the beam mode content at the output of a Raman laser based on a graded index multimode fiber.

Automated summary

We summarize our recent experimental studies on the nonlinear spatial reshaping of multimode beams at the output of multimode optical fibers. A holographic mode decomposition technique is used to reveal the variation of the spatial mode composition at the fiber output, caused by conservative (the Kerr effect) or dissipative (Raman scattering) nonlinear processes. We investigate the effect of spatial beam self-cleaning and compare experimental results with thermodynamic theory predictions, including beams carrying non-zero orbital angular momentum. Additionally, we analyze the beam mode content at the output of a Raman laser based on a graded index multimode fiber.