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Nonlinearity in optics and natural systems

English title Nonlinearity in optics and natural systems
Applicant Kasparian Jérôme
Number 175697
Funding scheme Project funding (Div. I-III)
Research institution GAP-Optique Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Other disciplines of Physics
Start/End 01.02.2018 - 31.01.2022
Approved amount 385'210.00
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All Disciplines (2)

Discipline
Other disciplines of Physics
Other disciplines of Environmental Sciences

Keywords (7)

Filamentation; climate; Femtosecond laser; tipping point; Non-linear optics; rogue wave; Modelling

Lay Summary (French)

Lead
Nonlinéarités : de l'optique aux systèmes naturels
Lay summary
La non-linéarité des équations décrivant les systèmes naturels ainsi que les rétroactions entre sous-systèmes induisent des comportements spécifiques. En particulier, ils peuvent résulter dans l'apparition d'événements extrêmes comme les vagues scélérates, ainsi que dans des points de basculement où un système change radicalement de régime sous l'influence de l'évolution graduelle d'un paramètre de contrôle (tel que la température) lorsqu'il atteint un seuil. Or, de tels changements de régimes peuvent avoir des conséquences catastrophiques, mais restent extrêmement difficiles à prévoir.

Je propose d'étudier ces événements extrêmes et ces points de basculement dans les systèmes naturels grâce à des analogies avec des systèmes physiques représentés par les mêmes jeux d'équations. nous nous intéresserons notamment à l'optique non-linéaire, et en particulier à la filamentation laser. Pour cela, notre travail s'articulera dans trois directions simultanément.

D'une part, nous étudierons expérimentalement au laboratoire et numériquement des structures optiques bidimensionnelles (guides d'onde planaires) pour développer un analogue d'une surface océanique bidimensionnelle. En parallèle, nous évaluerons la pertinence des événements extrêmes en tant qu'indicateurs précurseurs de points de bascules, dans des systèmes physiques (filamentation perturbée par la turbulence) autant que naturels (climat). Nous développerons également des modèles simplifiés propres à fournir une compréhension intuitive, avant d'étudier également des séries historiques, telles que l'englacement du Groenland, grâce à des modèles climatiques globaux et régionaux.

Enfin, au vu de l'influence du vent sur la croissance des vagues scélérates et sur leur spectre, nous perfectionnerons sa modélisation dans les modèles hydrodynamiques. Nous nous intéresserons spécialement à l'équilibre entre le vent et la viscosité : ces effets seront également testés expérimentalement dans des bassins de grande dimension équipés de soufflerie.

Grâce à l'association de nouvelles descriptions des phénomènes naturels non-linéaires et au transfert des connaissances déjà acquises dans le domaine de l'optique non-linéaire, nous contribuerons à une meilleure compréhension des points de bascule dans les systèmes complexes, de manière à réduire les dégâts qu'ils occasionnent.
Direct link to Lay Summary Last update: 29.09.2017

Responsible applicant and co-applicants

Employees

Publications

Publication
Reconciling different formulations of viscous water waves and their mass conservation
Eeltink D., Armaroli A., Brunetti M., Kasparian J. (2020), Reconciling different formulations of viscous water waves and their mass conservation, in Wave Motion, 97, 102610-102610.
Stabilization of uni-directional water wave trains over an uneven bottom
Armaroli Andrea, Gomel Alexis, Chabchoub Amin, Brunetti Maura, Kasparian Jérôme (2020), Stabilization of uni-directional water wave trains over an uneven bottom, in Nonlinear Dynamics, 101(2), 1131-1145.
Quantitative analysis of self-organized patterns in ombrotrophic peatlands
Béguin Chloé, Brunetti Maura, Kasparian Jérôme (2019), Quantitative analysis of self-organized patterns in ombrotrophic peatlands, in Scientific Reports, 9(1), 1499-1499.
Single-spectrum prediction of kurtosis of water waves in a nonconservative model
Eeltink D., Armaroli A., Ducimetière Y. M., Kasparian J., Brunetti M. (2019), Single-spectrum prediction of kurtosis of water waves in a nonconservative model, in Physical Review E, 100(1), 013102-013102.
Viscous damping of gravity-capillary waves: Dispersion relations and nonlinear corrections
Armaroli Andrea, Eeltink Debbie, Brunetti Maura, Kasparian Jérôme (2018), Viscous damping of gravity-capillary waves: Dispersion relations and nonlinear corrections, in Physical Review Fluids, 3(12), 124803-124803.
Energy conservation in self-phase modulation
Béjot P., Kasparian J. (2018), Energy conservation in self-phase modulation, in Physical Review A, 97(6), 063835-063835.

Collaboration

Group / person Country
Types of collaboration
Amin Chabchoub / University of Sydney Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel

Associated projects

Number Title Start Funding scheme
155970 From non-linear optics to oceanic rogue waves 01.02.2015 Project funding (Div. I-III)

Abstract

Due to intrinsic non-linearity of the equations at play (e.g., fluid dynamics), as well as numerous cross-interactions between sub-systems, many natural systems including the climate are highly nonlinear. This nonlinearity implies the occurrence of extreme events like oceanic rogue waves, as well as tipping points in which the system dramatically changes its state (e.g., the ice cover over sea or Greenland). While such events and changes can have severe human consequences, their prediction is still a challenge.I propose to investigate these extreme events and changes in natural non-linear systems by buinding on analogies between natural and physical systems sharing the same driving equations. I will especially focus on non-linear optics, in particular laser filamentation. In that purpose, we propose to work in three directions simultaneously.First, we will investigate, both experimentally at the laboratory scale and numerically, the ability of non-linear optics guided in one dimension by a sandwich structure to provide a realistic analogue of a two-dimensional sea surface. A particular attention will be dedicated to isolate the effect of the guiding reducing the system dimensionality, from the effect of beam geometry, by comparing the two-dimensional propagation with that of highly elliptical beams.In parallel, we will evaluate the relevance of the statistics of extreme events, summarized in a « rogueness index », as an early warning for dramatic changes or tipping points in a physical system. We will use turbulence-perturbed filamentation as a first benchmark, by progressively increasing the laser incident power considered as the system forcing parameter. Similar « rogueness indices » will be sought for simple systems like the Ising model, where numerical investigation is easier. This will allow us to tune the optimal definition of the « rogueness index » before applying it to the sea ice cover, based on both column and general-circulation models.Finally, considering the influence of wind on the wave growth and their spectrum, we will refine its modelling in the hydrodynamics propagation equation. A particular care will be dedicated to the balance between wind and losses due to viscosity, as we showed that they cannot exactly balance due to the contribution of different orders in steepness. The critical regime where wind and viscosity balance each other at one order but an unbalance persists at higher orders will be particularly investigated, both numerically and experimentally, first at a reduced scale, and then in a large-scale wavetank.By both creating new descriptions of highly non-linear natural phenomena and transferring existing knowledge from non-linear optics, we expect to contribute to a better understanding of dramtic system changes and tipping points, in the aim or reducing the associated dammage and fatalities.
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