TY - JOUR

T1 - Statistical mechanics of beam self-cleaning in GRIN multimode optical fibers

AU - Mangini, F.

AU - Gervaziev, M.

AU - Ferraro, M.

AU - Kharenko, D. S.

AU - Zitelli, M.

AU - Sun, Y.

AU - Couderc, V.

AU - Podivilov, E. V.

AU - Babin, S. A.

AU - Wabnitz, S.

N1 - Funding Information: Acknowledgments. We acknowledge support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant No. 740355), the Italian Ministry of University and Research (R18SPB8227), and the Russian Ministry of Science and Education Grant No. 14.Y26.31.0017. S.B., E.P., D.Kh. and M.G. were supported by Russian Science Foundation (Grant No. 21-42-00019). Funding Information: Funding. European Research Council (740355); Ministero dell’Istruzione, dell’Università e della Ricerca (R18SPB8227); Ministry of Education and Science of the Russian Federation (14.Y26.31.0017); Russian Science Foundation (21-42-00019). Publisher Copyright: © 2022 Optica Publishing Group.

PY - 2022/3/28

Y1 - 2022/3/28

N2 - Since its first demonstration in graded-index multimode fibers, spatial beam selfcleaning 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 comprehensive 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.

AB - Since its first demonstration in graded-index multimode fibers, spatial beam selfcleaning 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 comprehensive 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.

UR - http://www.scopus.com/inward/record.url?scp=85126654564&partnerID=8YFLogxK

U2 - 10.1364/OE.449187

DO - 10.1364/OE.449187

M3 - Article

C2 - 35473042

AN - SCOPUS:85126654564

VL - 30

SP - 10850

EP - 10865

JO - Optics Express

JF - Optics Express

SN - 1094-4087

IS - 7

ER -