Statistical mechanics of beam self-cleaning in GRIN multimode optical fibers

Abstract

Since its first demonstration in graded-index multimode fibers, spatial beam self-cleaning has attracted a growing research interest. It allows for the propagation of beams with a bell-shaped spatial profile, thus enabling the use of multimode fibers for several applications, from biomedical imaging to high-power beam delivery. So far, beam self-cleaning has been experimentally studied under several different experimental conditions. Whereas it has been theoretically described as the irreversible energy transfer from high-order modes towards the fundamental mode, in analogy with a beam condensation mechanism. Here, we provide a definitive theoretical description of beam self-cleaning, by means of a semi-classical statistical mechanics model of wave thermalization. This approach is confirmed by an extensive experimental characterization, based on a holographic mode decomposition technique, employing laser pulses with temporal durations ranging from femtoseconds up to nanoseconds. An excellent agreement between theory and experiments is found, which demonstrates that beam self-cleaning can be fully described in terms of the basic conservation laws of statistical mechanics.

References in corpus (6)

• Thermodynamic theory of highly multimoded nonlinear optical systems
• Soliton trapping in multimode fibers with random mode coupling
• Equivalence and nonequivalence of ensembles: Thermodynamic, macrostate, and measure levels
• Dramatic acceleration of wave condensation mediated by disorder in multimode fibers
• Nonlinear beam self-imaging and self-focusing dynamics in a GRIN multimode optical fiber: theory and experiments
• Wavefront shaping for optimized many-mode Kerr beam self-cleaning in graded-index multimode fiber

Cited by in corpus (15)

• Thermalization of orbital angular momentum beams in multimode optical fibers
• Observation of light thermalization to negative temperature Rayleigh-Jeans equilibrium states in multimode optical fibers
• Interplay of thermalization and strong disorder: Wave turbulence theory, numerical simulations, and experiments in multimode optical fibers
• Multimode optical fiber beam-by-beam cleanup
• Nature of Optical Thermodynamic Pressure Exerted in Highly Multimoded Nonlinear Systems
• Observation of Joule-Thomson photon-gas expansion
• Rayleigh-Jeans thermalization vs beam cleaning in multimode optical fibers
• Obstruction to ergodicity in nonlinear Schrödinger equations with resonant potentials
• Random matrix model of Kolmogorov-Zakharov turbulence
• Thermalization of the Ablowitz-Ladik lattice in the presence of non-integrable perturbations
• Coherence properties of light in highly multimoded nonlinear parabolic fibers under optical equilibrium conditions
• Spatio-temporal thermalization and adiabatic cooling of guided light waves
• Universal Routing of Light via Optical Thermodynamics
• Spatio-temporal equilibrium thermodynamics of guided optical waves at positive and negative temperatures
• Irreversible thermalization vs reversible dynamics mediated by anomalous correlators: Wave turbulence theory and experiments in optical fibers