MODE DECOMPOSITION METHOD FOR INVESTIGATING THE NONLINEAR DYNAMICS OF A MULTIMODE BEAM
M. Gervaziev1,2, M. Ferraro3, E. V. Podivilov1,2, F. Mangini3, O.S. Sidelnikov2, D.S. Kharenko1,2, M. Zitelli3, M.P. Fedoruk2, S.A. Babin1,2, S. Wabnitz2,3
1Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
3Sapienza University of Rome, Rome, Italy
Keywords: Mode decomposition, thermalization, multimode fiber
Abstract
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 us 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.
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