8:30am - 9:00amInvitedID: 287
/ TOM6 S06: 1
TOM 6 Nonlinear and Quantum Optics
Thermalization of light waves in multimode optical fibers: Negative temperatures equilibrium states and the role of disorder
Kilian Baudin1, Josselin Garnier2, Nicolas Berti1, Adrien Fusaro3, Lucas Zanaglia4, Claire Michel4, Valérie Doya4, Katarzyna Krupa5, Guy Millot1, Antonio Picozzi1
1CNRS - Université de Bourgogne, ICB, Dijon, France; 2CMAP, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, France; 3CEA, DAM, Arpajon, France; 4Université Côte d’Azur, CNRS, Institut de Physique de Nice, Nice, France; 5Institute of Physical Chemistry Polish Academy of Sciences, Warsaw, Poland
Nonlinear random waves exhibit a phenomenon of irreversible thermalization, in analogy with the thermalization of a classical gas system. This irreversible process of thermalization to the Rayleigh-Jeans equilibrium distribution has been recently observed experimentally in multimode optical fibers. Here we discuss a recent progress along two different directions. Firstly, we report the observation of thermalization to negative temperature equilibrium states, in which high-order fiber modes are more populated than low-order modes. Secondly, we analyze the impact of disorder inherent to light propagation in multimode fibers. We identify an unexpected regime in which strong random coupling among non-degenerate modes leads to a nonequilibrium process of thermalization.
9:00am - 9:15amID: 364
/ TOM6 S06: 2
TOM 6 Nonlinear and Quantum Optics
Full-beam spatial coherence measurements of supercontinuum generation in multimode fibers
Jiaqi Li, Piotr Ryczkowski, Goëry Genty
tampere university, Finland
We study experimentally the spatial coherence across the full spatial beam profile of supercontinuum light generated in both in graded-index and step-index multimode fibers. We observe a decrease of the coherence area with an increase of the injected pump power. Numerical simulations based on linearly polarized modes and mode coupling theory are in good agreement with our experiments and indicate that the decrease of coherence area is strongly related to a change in the modal amplitude distribution.
9:15am - 9:30amID: 360
/ TOM6 S06: 3
TOM 6 Nonlinear and Quantum Optics
Mid-infrared generation beyond 3.5 μm in a graded-index silica fiber
Karolina Stefańska1,2, Pierre Béjot1, Julien Fatome1, Guy Millot1, Karol Tarnowski2, Bertrand Kibler1
1Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR6303 CNRS-Université de Bourgogne, Dijon, France; 2Department of Optics and Photonics, Wrocław University of Science and Technology, Wrocław, Poland
We present theoretical as well as experimental evidence of far-detuned nonlinear wavelength conversion towards the mid-infrared, namely beyond 3.5 μm, in a few-mode graded-index silica fiber pumped at 1.064 μm. We take into account the full frequency-dependence of the propagation constants, which allows us to obtain excellent agreement of theoretical predictions with experimental observations and provides new and accurate interpretation of intramodal and intermodal four-wave mixing processes in few-mode fibers.
9:30am - 10:00amInvitedID: 275
/ TOM6 S06: 4
TOM 6 Nonlinear and Quantum Optics
Beam-by-beam Kerr clean-up in multimode optical fibres
Mario Ferraro1,2, Fabio Mangini1, Yann Leventoux3, Alessandro Tonello3, Mario Zitelli1, Yifan Sun1, Sebastien Fevrier3, Katarzyna Krupa4, Denis Kharenko5,6, Stefan Wabnitz1, Vincent Couderc3
1DIET, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy; 2Department of Physics, University of Calabria, Via P. Bucci, 87069 Rende, Italy; 3XLIM, UMR CNRS 7252, University of Limoges, 123 Avenue A. Thomas, 87060 Limoges, France; 4Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland; 5Institute of Automation and Electrometry SBRAS, 1 ac. Koptyug ave., Novosibirsk 630090, Russia; 6Novosibirsk State University, Novosibirsk 630090, Russia
We propose and demonstrate the concept of beam-by-beam cleaning in multimode optical fibres, i.e., the increase of the spatial quality of an intense laser beam, induced by a relatively weak, quasi singlemode seed beam. This effect, which relies on the Kerr nonlinearity of the fibre, is quite efficient: a seed beam is capable of providing a bell-shape to a ten times more powerful beam. Our results pave the way for the development of a new class of all-optical switching devices for intense laser beams.
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