Experimental observation of the 1D Kerr-Type cavity soliton Temporal cavity solitons constitute a remarkable family of light pulses. They don’t spread nor suffer losses and circulate indefinitely, round-trips after round-trips, along the closed path of a nonlinear cavity. To maintain their shape and power, they simply draw some energy from a continuous-wave external beam. Being robust attracting states, they can be easily written by an external pulse and naturally provide reshaping and wavelength conversion functionalities. We experimentally demonstrated the generation of such solitons. We were able to provide precise temporal and spectral characterization along with long-term observation. We also wrote the solitons in pairs and in data streams, showing that our fiber cavity could potentially be used as an all- optical buffer capable of storing 45,000 bits at 25G bits/s. These results have been recently published in Nature Photonics High repetition-rate pulse train generation through dissipative modulation instability in a passive fiber resonator In the early 90’s, a cavity configuration which allows for the generation of stable pulse trains through dis- sipative modulational instability was proposed. The experimental implementation of the so-called MI laser was demonstrated a few years later. Although the ideal parameters for the generation of a pulse train with a repetition rate in the THz range are easily deduced from the theory, no realization in that frequency range has been reported due to practical issues. Thanks to the tuning of the overall cavity dispersion based on the use of special fibers, we recently demonstrated the generation of a 1.6 THz repetition-rate optical pulse-train. Theoretical and experimental study of nonlinear symmetry breaking induced by the order dispersion in a passive fiber resonator In the regime of dissipative modulational instability, the repetition-rates of the generated pulse train can be tuned by changing the group-velocity dispersion (GVD) of the fiber. To reach the THz range, one has to drastically reduced the total GVD in the cavity. In that case, the next order of dispersion has to be included in the theoretical model describing the evolution of the intracavity field (here the mean field model). The third-order dispersion induces a drift of the pattern and an asymmetry in the spectrum. Both these effects can be precisely calculated by a multi-scale model describing the field evolution above threshold. This theoretical work has been confirmed by experimental measurements of the spectral asymmetry.

betaLorsque des réactions chimiques non-linéaires évoluent loin de leur état d'équilibre thermodynamique et sont couplées au processus de transport par diffusion moléculaire, des instabilités spatiales et spatio-temporelles peuvent apparaître. Dans un réacteur chimique entretenu par des flux de réactifs, nous étudions de tels systèmes de réaction-diffusion mis en oeuvre dans des gels de polyélectrolytes. Les variations volumiques du gel induites par les changements d'état chimique de la réaction génèrent une grande variété de structures morphologiques stationnaires ou dynamiques. Les changements de tailles du gel support contribuent à faire naître de nouvelles instabilités. Nous tentons de comprendre la contribution apportée par les différents processus (réaction-diffusion, changement de taille) sur la dynamique résultante du système. Ces études participent à la conception de nouveaux systèmes "intelligents" autonomes.

Experimental observation of the 1D Kerr-Type cavity soliton<p><p>Temporal cavity solitons constitute a remarkable family of light pulses. They don’t spread nor suffer losses and circulate indefinitely, round-trips after round-trips, along the closed path of a nonlinear cavity. To maintain their shape and power, they simply draw some energy from a continuous-wave external beam. Being robust attracting states, they can be easily written by an external pulse and naturally provide reshaping and wavelength conversion functionalities. We experimentally demonstrated the generation of such solitons. We were able to provide precise temporal and spectral characterization along with long-term observation. We also wrote the solitons in pairs and in data streams, showing that our fiber cavity could potentially be used as an all- optical buffer capable of storing 45,000 bits at 25G bits/s. These results have been recently published in Nature Photonics<p><p>High repetition-rate pulse train generation through dissipative modulation instability in a passive fiber resonator<p><p>In the early 90’s, a cavity configuration which allows for the generation of stable pulse trains through dis- sipative modulational instability was proposed. The experimental implementation of the so-called MI laser was demonstrated a few years later. Although the ideal parameters for the generation of a pulse train with a repetition rate in the THz range are easily deduced from the theory, no realization in that frequency range has been reported due to practical issues. Thanks to the tuning of the overall cavity dispersion based on the use of special fibers, we recently demonstrated the generation of a 1.6 THz repetition-rate optical pulse-train.<p><p>Theoretical and experimental study of nonlinear symmetry breaking induced by the order dispersion in a passive fiber resonator<p><p>In the regime of dissipative modulational instability, the repetition-rates of the generated pulse train can be tuned by changing the group-velocity dispersion (GVD) of the fiber. To reach the THz range, one has to drastically reduced the total GVD in the cavity. In that case, the next order of dispersion has to be included in the theoretical model describing the evolution of the intracavity field (here the mean field model). The third-order dispersion induces a drift of the pattern and an asymmetry in the spectrum. Both these effects can be precisely calculated by a multi-scale model describing the field evolution above threshold. This theoretical work has been confirmed by experimental measurements of the spectral asymmetry. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Cette thèse a pour objet d’aborder l’information en tant que lien essentiel entre les sciences de la nature et les sciences humaines. Il y est principalement fait état de principes de la science physique, alliés à un ensemble d’approches scientifiques issues, notamment, des théories de la complexité, du chaos, de l’information, de l’auto-organisation, des émergences et des écosystèmes. Les lois de la thermodynamique jouent un rôle central dans ce contexte, où l’organisation et la néguentropie sont directement inscrites dans le champ de la production d’informations. Il y est en particulier fait référence à la Loi de maximisation d’entropie (ou, autrement dit, de dissipation d’énergie), dont l’incidence sur le fonctionnement et le comportement des structures dissipatives que sont les humains est soulignée via un large éventail d’exemples pris dans la vie courante, incidences fondées à la base sur le rôle omniprésent de l’information. L’approche systémique, à laquelle il est fait appel dans un certain nombre de considérations, conduit ici à souligner en profondeur les incidences interactives de l’environnement (l’écosystème) - et des principes de la sélection naturelle qui le déterminent - avec le comportement humain et les phénomènes d’information qui définissent celui-ci. Les applications de l’approche globale de cette thèse s’expriment dans une grande variété de domaines, dont également ceux de la survie, du bien-être, de la conversation et de la robotique. / This thesis aims at considering the information as essential link between the sciences of the nature and the human sciences. It is mainly refered to principles of the natural science, allied in a set of scientific stemming approaches, in particular, theories of the complexity, of chaos, of information, auto-organization, emergences and ecosystems. The laws of the thermodynamics play a central role in this context, where the organization and the negentropy make directly part of the field of information production. There is in particular refered to Law of maximization of entropy Production (or, in other words, of energy dissipation), among which the incidence on the functioning and the behavior of the human being as a dissipative structure is underlined via a wide range of examples taken in the common life, incidence basically established on the omnipresent role of the information. The systemics approach, to which it is brought up in a number of considerations, leads here to underline the interactive incidences of the environment (the ecosystem) - linked to the principles of the natural selection which determines its evolution - with the human behavior linked to the information phenomena which define it. The applications of the global approach of this thesis appear in a broad variety of domains, of which also those of the survival, the well-being, the conversation and robotics.