55 research outputs found

    Supercontinuum Spectrum Engineering in Ge-doped Microstructured Multicore Fiber

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    Supercontinuum generation in a multicore Ge-doped microstructured optical fiber is experimentally studied. The output spectral extension and the presence of four-wave mixing peaks are strongly dependent on the level of doping.3 page(s

    Interfaces detection after corneal refractive surgery by low coherence optical interferometry

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    The detection of refractive corneal surgery by LASIK, during the storage of corneas in Eye Banks will become a challenge when the numerous operated patients will arrive at the age of cornea donation. The subtle changes of corneal structure and refraction are highly suspected to negatively influence clinical results in recipients of such corneas. In order to detect LASIK cornea interfaces we developed a low coherence interferometry technique using a broadband continuum source. Real time signal recording, without moving any optical elements and without need of a Fourier Transform operation, combined with good measurement resolution is the main asset of this interferometer. The associated numerical processing is based on a method initially used in astronomy and offers an optimal correlation signal without the necessity to image the whole cornea that is time consuming. The detection of corneal interfaces - both outer and inner surface and the buried interface corresponding to the surgical wound – is then achieved directly by the innovative combination of interferometry and this original numerical process

    Etude de rayonnements à large bande spectrale induits dans les fibres optiques microstructurées air-silice

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    Thèse université de Limoge

    Etude de rayonnements à large bande spectrale induits dans les fibres optiques microstructurées air-silice

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    Les travaux reportés dans ce manuscrit de thèse portent sur la génération de supercontinua dans les fibres optiques microstructurées air-silice. Le développement d un nouveau système basé sur une double excitation de la fibre non linéaire (fondamental et harmonique) a permis l obtention d un supercontinuum dans le domaine infrarouge et visible. Après une étude systématique du phénomène, il a été montré que l élargissement dans l infrarouge était induit par une propagation soliton et que le continuum visible était généré par un effet de modulation de phase croisée. Deux nouvelles méthodes innovantes, issues de ces premières investigations, sont présentées. La première technique utilise la génération de second harmonique obtenue directement dans la fibre. La seconde technique est basée sur un mélange à quatre ondes intermodal particulier. Ces études ont été réalisées pour le développement d outils de diagnostic pour la cytométrie de flux et l imagerie non linéaire CARS.The investigations reported here concerns the generation of supercontinua in air-silica microstructured optical fibres. The development of a new system based on a double excitation (fundamental and harmonic) of nonlinear fibre allowed to obtain a supercontinuum in the infra-red and visible range. After a systematic study of the phenomenon, it was shown that the broadenings in the infra-red and in visible domains were generated by soliton propagations and cross phase modulation respectively. Then two new innovating methods, resulting from the double pumping device, were demonstrated. The first technique uses the second harmonic generation obtained directly in the fibre. The second one is based on a particular intermodal four wave mixing. These studies were carried out for the development of diagnosis tools for the flow cytometry and the nonlinear CARS imaging.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

    Visible supercontinuum generation in holey fibers by dual-wavelenght nanosecond pumping

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