La recherche d'une langue parfaite a fascine les auteurs de science-fiction de l'ecole campbellienne. L'article retrace l'engagement de quelques-uns d'entre eux, derriere Robert Heinlein et John Campbell, dans... more
La recherche d'une langue parfaite a fascine les auteurs de science-fiction de l'ecole campbellienne. L'article retrace l'engagement de quelques-uns d'entre eux, derriere Robert Heinlein et John Campbell, dans l'etude de la "semantique generale" d'Alfred Korzybski, puis le detournement de ces idees vers la "Dianetique" de L. Ron Hubbard, jusqu'a la fondation de la "Scientologie".
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Stimulated Brillouin scattering (SBS) of visible light in a small-core photonic crystal fiber (PCF) resonator of small external Q-factor, experimentally presents trains of subluminous and superluminous pulses presenting all the... more
Stimulated Brillouin scattering (SBS) of visible light in a small-core photonic crystal fiber (PCF) resonator of small external Q-factor, experimentally presents trains of subluminous and superluminous pulses presenting all the characteristics of dissipatif Brillouin solitons. Insertion of the acoustic dispersion, which may be significant in PCF, in the coherent SBS three-wave model modify the dissipative structures. For special pump wavelengths the acoustic dispersion response may be particularly strong and may lead to an enhanced Brillouin mirror.
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International audienc
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International audienc
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or... more
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Identification de compétences (pré-)scientifiques chez des élèves d’école maternelle : de l’utilité de croiser les cadres théoriques pour l’analyse émergente d’une vidéo Estelle Blanquet, Christina Siry, Éric Picholle
Research Interests: Sociology and Humanities
Lasers are often perceived as threshold devices, with a rapid all-or-nothing transition around threshold. This approach usually holds for high quality factor (“Class A”) devices or macroscopic ones, but fails to correctly describe the... more
Lasers are often perceived as threshold devices, with a rapid all-or-nothing transition around threshold. This approach usually holds for high quality factor (“Class A”) devices or macroscopic ones, but fails to correctly describe the transition in very small components. The long carrier lifetime – compared to the cavity time – typical of semiconductor-based micro- and nanolasers (“Class B” devices) introduces an additional element of complexity to the problem due to the nonlinear dynamical evolution of the coherent fraction of electromagnetic field, and opens questions on coherence buildup. Below threshold, the characterization of the latter is rendered difficult due to the small number of photons contained in the laser cavity at any given time, thus yielding very low optical intensity levels, close to or below the sensitivity limit of standard photodetectors. Fortunately, recent telecom-based quantum measurement techniques now allow the indirect characterization of the laser’s response through its second order correlation function, g^(2)(τ).
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While usually negligible in standard optical fibers, the group velocity dispersion of acoustic waves may in some cases play a significant role in the dynamics of stimulated Brillouin scattering (SBS) in propagation media with more complex... more
While usually negligible in standard optical fibers, the group velocity dispersion of acoustic waves may in some cases play a significant role in the dynamics of stimulated Brillouin scattering (SBS) in propagation media with more complex structures, such as microstructured fibers. The usual three-wave coherent model of SBS can be adapted to take perturbative acoustic dispersion into account, but the slowly varying envelope approximation does not hold for stronger values of the acoustic dispersion, which call for a more sophisticated inertial model of SBS. A new regime of SBS mirrors with a spatially inverted acoustic profile is predicted in this limit. In the presence of strong acoustic dispersion, this regime exhibits a higher conversion efficiency than the usual mirror in the dispersionless case, as well as nonlinear self-stabilization of the phase of the acoustic wave when the pump is strongly depleted. Formal calculations allow the identification of regions of strong dynamic di...
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We discuss the stability of a Brillouin fiber ring reso-nator used as an active delay line. The stability and shape of the output pulse train depends only on the pump power and the ring recoupling coefficient. The amplified spontaneous... more
We discuss the stability of a Brillouin fiber ring reso-nator used as an active delay line. The stability and shape of the output pulse train depends only on the pump power and the ring recoupling coefficient. The amplified spontaneous noise is shown to be irrelevant, and an optimized ...
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La mesure du taux de coincidence de photons emis par des lasers a semiconducteurs operant dans la region du seuil permet de caracteriser leur route d'etablissement de la coherence. Nous mettons egalement en evidence des valeurs de... more
La mesure du taux de coincidence de photons emis par des lasers a semiconducteurs operant dans la region du seuil permet de caracteriser leur route d'etablissement de la coherence. Nous mettons egalement en evidence des valeurs de g^(2)(0) > 2.
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While duly Copernican, a significant part of primary school teachers-in-training fail to see the point of the (Galilean) principle of relativity. Two inquiry based teaching sequences involving the notion of reference frame were designed... more
While duly Copernican, a significant part of primary school teachers-in-training fail to see the point of the (Galilean) principle of relativity. Two inquiry based teaching sequences involving the notion of reference frame were designed to challenge the students' robust pre-Galilean misconceptions, without mathematical requirements. The first sequence makes use of an artist view ("Framed Earth", by Manchu, 1989) and literary representations of the Earth as seen from a lunar point of view. The second one deals with the succession of seasons through analogical models of the Earth/Sun system. Both sequences were tested among future primary school teachers. Half the cohort was only exposed to the latter sequence while the other half experimented both. Artist representations appear to be an effective way to challenge misconceptions where direct experimentation is not available, such as in astronomy problems.
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Pour aider le lecteur a se representer ces univers etrangers, les auteurs et les theoriciens de la SF ont developpe une «mecanique science-fictionnelle» desormais eprouvee. Cet article s'interesse plus particulierement au concept... more
Pour aider le lecteur a se representer ces univers etrangers, les auteurs et les theoriciens de la SF ont developpe une «mecanique science-fictionnelle» desormais eprouvee. Cet article s'interesse plus particulierement au concept d’encyclopedie, introduit par le semioticien Umberto Eco, et a ses declinaisons dans les univers de la science-fiction. Il propose une typologie des mondes imaginaires, de l'allotopie et de l'utopie, l'uchronie, la metatopie, l'heterotopie, les modeles scientifiques pouvant alors etre consideres comme des "haplotopies" (i.e. des lieux simplifies).
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La prise en compte de l'ouverture numerique finie des fibres optiques unimodales nous permet de distinguer la retrodiffusion brillouin stimulee (dbs) et la diffusion brillouin de gaine (dbg), moins connue, qui sont respectivement... more
La prise en compte de l'ouverture numerique finie des fibres optiques unimodales nous permet de distinguer la retrodiffusion brillouin stimulee (dbs) et la diffusion brillouin de gaine (dbg), moins connue, qui sont respectivement l'interaction de la lumiere avec des ondes acoustiques axiale de tres haute frequence (34 ghz) et transverse (5-1000 mhz) ; nous en etablissons les modeles coherents a trois ondes (pompe-brillouin-acoustique). Une seconde partie, essentiellement experimentale, en decrit la dynamique non lineaire, en bon accord qualitatif et quantitatif avec les simulations numeriques. La stabilite des lasers brillouin (dbs) apparait limitee par leur longueur. Des instabilites liees a la dbg interviennent pour les resonateurs a tres longues fibres optiques, que nous utilisons pour mettre en evidence une modulation croisee d'amplitude. Nous etudions ensuite le couplage des deux mecanismes, et la dynamique non lineaire a quatre ondes associee en tenant compte d'une seule resonance acoustique transverse. De nouveaux regimes complexes sont obtenus, comme des impulsions brillouin tres larges (200 ns) fortement modulees aux frequences dbg. On s'interesse tout particulierement a l'elargissement et a la compression d'impulsions non modulees. Bien que la dbg soit a priori perturbative, on observe dans certains cas des structures quasi-solitoniques etroites (18 ns), comprimees d'un facteur 2 par rapport a celles observees dans des lasers brillouin a fibre courte. Une etude numerique systematique montre que le parametre de controle de ce nouveau mecanisme est le rapport entre l'intervalle spectral libre de la cavite et la frequence dbg en cause. Enfin, une quatrieme partie aborde l'etude du probleme a n ondes (tous les modes acoustiques transverses participant) et met en evidence l'importance de modes acoustiques se propageant dans le manteau mecanique de la fibre, avant de tirer les consequences de cette etude pour les applications de type telecommunications.
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Summary from only given. Stimulated Brillouin scattering (SBS) of a cw pump Ep in an optical fiber is able to generate a counter propagating Stokes pulse EB by resonant interaction with high frequency (GHz) axial acoustic waves Ea. We... more
Summary from only given. Stimulated Brillouin scattering (SBS) of a cw pump Ep in an optical fiber is able to generate a counter propagating Stokes pulse EB by resonant interaction with high frequency (GHz) axial acoustic waves Ea. We have dynamically described and experimentally obtained the generation of stable trains of dissipative Brillouin solitons in fiber ring lasers below a
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ELSEVIER Optics Communications 135 (1997) 327330 15 February 1997 OPTICS COMMUNICATIONS Guidedacousticwave resonances in the dynamics of a stimulated Brillouin fiber ring laser Eric Picholle ', Antonio Picozzi CNRS, Laboratoire... more
ELSEVIER Optics Communications 135 (1997) 327330 15 February 1997 OPTICS COMMUNICATIONS Guidedacousticwave resonances in the dynamics of a stimulated Brillouin fiber ring laser Eric Picholle ', Antonio Picozzi CNRS, Laboratoire de Physique de la Matiere Condensee, ...
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Abstract : Generation of large-scale spatio-temporal coherent structures caused by stimulated Brillouin backscattering of a narrow-band laser wave in a large-gain one-dimensional nonlinear medium is studied by comparing the numerical... more
Abstract : Generation of large-scale spatio-temporal coherent structures caused by stimulated Brillouin backscattering of a narrow-band laser wave in a large-gain one-dimensional nonlinear medium is studied by comparing the numerical simulations and the analytical asymptotics ...
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Research Interests: Physics, Nonlinear dynamics, Medicine, Fiber Laser, Mathematical Sciences, and 11 moreStimulated Brillouin Scattering, Physical sciences, Stability Analysis, Bifurcation, CHEMICAL SCIENCES, Self Organization, Symmetry Breaking, Rayleigh Scattering, Hopf Bifurcation, Brillouin zone, and Critical value
Research Interests: Applied Mathematics, Materials Science, Optics, Medical Imaging, Fiber Optics, and 15 moreTelecommunications, Nonlinear Optics, Photonics, Fiber Laser, Society, Stimulated Brillouin Scattering, Optical, Light, Optical physics, Optical fiber, Non Linear Optics, Optical Fibers, Round Trip Time, Brillouin Scattering, and Electrical And Electronic Engineering
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Du point de vue de l’enseignement des sciences, il est beaucoup plus fructueux de considerer une fiction sous l’aspect de la plausibilite que sous celui de la verite. Des problematiques et des traitements differents appelleront des... more
Du point de vue de l’enseignement des sciences, il est beaucoup plus fructueux de considerer une fiction sous l’aspect de la plausibilite que sous celui de la verite. Des problematiques et des traitements differents appelleront des questionnements differents et, si l’auteur est un tant soit peu subtil, les histoires contrefactuelles ne seront pas les moins interessantes a confronter a un regard scientifique. L'article propose une typologie des investigations envisageables autour de fictions improbables, du questionnement du contrat de lecture a celle de la coherence interne d'une histoire en passant par les questions factuelles, la "retro-ingenierie" de techniques de science-fiction, voire des experiences de pensee questionnant la science telle que nous la connaissons.
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Dans cet entretien, Ugo Bellagamba et Eric Picholle presentent les enjeux theoriques des Journees Science et Fiction de Peyresq, consacrees chaque annee a des reflexions sur les rapports entre la science-fiction et les differents champs... more
Dans cet entretien, Ugo Bellagamba et Eric Picholle presentent les enjeux theoriques des Journees Science et Fiction de Peyresq, consacrees chaque annee a des reflexions sur les rapports entre la science-fiction et les differents champs du savoir. Les actes des deux premieres editions, Robert Heinlein et la pedagogie du reel et Rudyard Kipling et l’enchantement de la technique sont disponibles sur le site REVEL de l’Universite de Nice Sophia-Antipolis : http://revel.unice.fr/symposia/scetfictions. Depuis cet entretien, la sixieme edition des Journees Interdisciplinaires Sciences et Fictions de Peyresq (17-20 mai 2012) a porte sur le theme de l’Intelligence artificielle.
Research Interests: Art and ReS Futurae
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The study aims to identify the participants’ representations of light and its propagation from a primary source through the closed space of a black box and in the absence of multiple diffusion and reflection. The elements of explanation... more
The study aims to identify the participants’ representations of light and its propagation from a primary source through the closed space of a black box and in the absence of multiple diffusion and reflection. The elements of explanation then involve two distinct notions: that light propagates in a straight line; and the necessity for the light to reach the eye in order to be seen. Counter-intuitively enough, in both countries, the percentage of correct answers decreases in a similar way as primary school school children grow up, to become a small minority among students at university (11% in Romania and 16 to 27% in France). Percentage of correct drawings among adults varies between 11% (Romanian future primary school teachers) and 27%. Comparaison with their written explanations reveals an excellent concordance.
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La prise en compte de la dispersion de vitesse de groupe acoustique permet d’envisager des amplificateurs Brillouin a bande large dans les fibres optiques microstructurees
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Apres un bref rappel des rapports qu'entretient la litterature de science-fiction avec la science, l'article revient sur trois strategies speculatives qu'elles developpent chacune a sa facon : l'extraction,... more
Apres un bref rappel des rapports qu'entretient la litterature de science-fiction avec la science, l'article revient sur trois strategies speculatives qu'elles developpent chacune a sa facon : l'extraction, l'extrapolation et l'hyperbole, et envisage leur rapport a des scenarios singuliers.
Des subjectivites collectives robustes sont automatiquement associees aux groupes sociaux correspondant a un paradigme scientifique dominant. Pour autant, ce ne sont pas les seuls possibles. Il arrive meme qu'une SC precede... more
Des subjectivites collectives robustes sont automatiquement associees aux groupes sociaux correspondant a un paradigme scientifique dominant. Pour autant, ce ne sont pas les seuls possibles. Il arrive meme qu'une SC precede l'explicitation de l'experience qui la sous-tend. L'article retrace, des theologies medievaux a Giordano Bruno, l'histoire minoritaire de la relativite galileenne avant Galilee, et discute les racines du double faux-sens classique sur la fameuse phrase que lui attribue le folklore populaire, "Et pourtant, elle tourne".
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ABSTRACT