Energy and wave-action flows underlying Rayleigh-Jeans thermalization of optical waves propagating in a multimode fiber

Year: 2021

Authors: Baudin K.; Fusaro A.; Garnier J.; Berti N.; Krupa K.; Carusotto I; Rica S.; Millot G.; Picozzi A.

Autors Affiliation: Univ Bourgogne Franche Comte, CNRS, Lab Interdisciplinaire Carnot de Bourgogne, Dijon, France; CEA, DAM, DIF, F-91297 Arpajon, France; Ecole Polytech, Inst Polytech Paris, CNRS, CMAP, F-91128 Palaiseau, France; Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland; Univ Trento, INO CNR BEC Ctr, I-38123 Povo, TN, Italy; Univ Adolfo Ibanez Penalolen, Santiago 7910000, Chile; Inst Univ France IUF, 1 Rue Descartes, F-75005 Paris, France.

Abstract: The wave turbulence theory predicts that a conservative system of nonlinear waves can exhibit a process of condensation, which originates in the singularity of the Rayleigh-Jeans equilibrium distribution of classical waves. Considering light propagation in a multimode fiber, we show that light condensation is driven by an energy flow toward the higher-order modes, and a bi-directional redistribution of the wave-action (or power) to the fundamental mode and to higher-order modes. The analysis of the near-field intensity distribution provides experimental evidence of this mechanism. The kinetic equation also shows that the wave-action and energy flows can be inverted through a thermalization toward a negative temperature equilibrium state, in which the high-order modes are more populated than low-order modes. In addition, a Bogoliubov stability analysis reveals that the condensate state is stable. Copyright (C) 2021 EPLA

Journal/Review: EUROPHYSICS LETTERS

Volume: 134 (1)      Pages from: 14001-1  to: 14001-7

KeyWords: BOSE-EINSTEIN CONDENSATION; TURBULENCE; TEMPERATURE; LIGHT
DOI: 10.1209/0295-5075/134/14001

Citations: 10
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