On spatial beam self-cleaning from the perspective of optical wave thermalization in multimode graded-index fibers

Year: 2023

Authors: Ferraro M., Mangini F., Zitelli M., Wabnitz S.

Autors Affiliation: Sapienza Univ Rome, DIET, Dept Informat Engn Elect & Telecommun, Rome, Italy; Univ Calabria, Dept Phys, Arcavacata Di Rende, Italy; CNR INO, Ist Nazl Ott, Pozzuoli, Italy.

Abstract: The input power-induced transformation of the transverse intensity profile at the output of graded-index multimode optical fibers from speckles into a bell-shaped beam sitting on a low intensity background is known as spatial beam self-cleaning. Its remarkable properties are the output beam brightness improvement and robustness to fiber bending and squeezing. These properties permit to overcome the limitations of multimode fibers in terms of low output beam quality, which is very promising for a host of technological applications. In this review, we outline recent progress in the understanding of spatial beam self-cleaning, which can be seen as a state of thermal equilibrium in the complex process of modal four-wave mixing. In other words, the associated nonlinear redistribution of the mode powers which ultimately favors the fundamental mode of the fiber can be described in the framework of statistical mechanics applied to the gas of photons populating the fiber modes. This description has been corroborated by a series of experiments by different groups. However, some open issues still remain, and we offer a perspective for future studies in this emerging and controversial field of research.

Journal/Review: ADVANCES IN PHYSICS-X

Volume: 8 (1)      Pages from: 2228018-1  to: 2228018-35

More Information: This work was supported by the European Research Council (ERC) under the EU HORIZON2020 Research and Innovation Program (740355, 101081871), Ministero dell’Universita e della Ricerca (R18SPB8227). F.M. was supported by the European Union under the Italian National Recovery and Resilience Plan (NRRP) of Next Generation EU, partnership on Telecommunications of the Future’ (PE00000001 – program RESTART’), and M.Z. by the Rome Technopole Flagship Project 5.
KeyWords: Kerr effect; Multimode fibers; Nonlinear optical fibers; Statistical mechanics; Thermodynamics; Graded-index fibers
DOI: 10.1080/23746149.2023.2228018

Citations: 10
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