Weak Langmuir turbulence in disordered multimode optical fibers

Abstract

We consider the propagation of temporally incoherent waves in multimode optical fibers (MMFs) in the framework of the multimode nonlinear Schrödinger (NLS) equation accounting for the impact of the natural structural disorder that affects light propagation in standard MMFs (random mode coupling and polarization fluctuations). By averaging the dynamics over the fast disordered fluctuations, we derive a Manakov equation from the multimode NLS equation, which reveals that the Raman effect introduces a previously unrecognized nonlinear coupling among the modes. Applying the wave turbulence theory on the Manakov equation, we derive a very simple scalar kinetic equation describing the evolution of the multimode incoherent waves. The structure of the kinetic equation is analogous to that developed in plasma physics to describe weak Langmuir turbulence. The extreme simplicity of the derived kinetic equation provides physical insight into the multimode incoherent wave dynamics. It reveals the existence of different collective behaviors where all modes self-consistently form a multimode spectral incoherent soliton state. Such an incoherent soliton can exhibit a discrete behavior characterized by collective synchronized spectral oscillations in frequency space. The theory is validated by accurate numerical simulations: The simulations of the generalized multimode NLS equation are found in quantitative agreement with those of the derived scalar kinetic equation without using adjustable parameters.

12 pages, 3 figures

References in corpus (8)

• Thermodynamic theory of highly multimoded nonlinear optical systems
• Nonlinear propagation in multi-mode fibers in the strong coupling regime
• Soliton trapping in multimode fibers with random mode coupling
• Dramatic acceleration of wave condensation mediated by disorder in multimode fibers
• Fast and accurate modelling of nonlinear pulse propagation in graded-index multimode fibers
• Wave condensation with weak disorder versus beam self-cleaning in multimode fibers
• Light focusing in the Anderson Regime
• Statistical physics of nonlinear wave interaction

Cited by in corpus (2)

• Feynman rules for forced wave turbulence
• Spatio-temporal equilibrium thermodynamics of guided optical waves at positive and negative temperatures