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Photoluminescence polaron dans le niobate de lithium : approche axpérimentale et modélisation

Abstract : Because of their electro-optical, non-linear optical and photorefractive effet, lithium niobate crystals (LN) are used in many applications such as modulation, filtering, holographic storage or frequency conversion. Its known that the photorefractive effect is influenced by both extrincic deep centers (Fe2+ and Fe3+ in most cases) and by niobium antisites (Nbli5+) which constitute preferential sites to trap an electron hence giving a small bound polaron (Nbli4+). This defect is characterized by a photo_indiced obsorption (API) broad band in the NIR range, as well as slightly Stokes shifted photoluminescence band (PL). We presnt nerein an experime,tal study of the polaron related PL in iron doped congruent lithium niobate as a function of temperature and incident intensity in CW and pulsed regime. We also propose a phenomenological threecenter model as an interpretation of all observed results. We show that the PL permits one to determine the concentration of deep centres in congruent LN in trace amounts, whatever their nature. For Fe 2+ ions, the sensitivity is typically around 0,25 ppm at RT, which is better than absorption spectroscopy. In addition, unlike other techniques, the PL is spatially resolved (micrometer scale) which allows to maps the concentration of deep donors, hence its potential for characterizating waveguides, integrated optical components and other microstructures
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Submitted on : Thursday, March 29, 2018 - 11:58:31 AM
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Aïssa Harhira. Photoluminescence polaron dans le niobate de lithium : approche axpérimentale et modélisation. Autre [cond-mat.other]. Université Paul Verlaine - Metz, 2007. Français. ⟨NNT : 2007METZ052S⟩. ⟨tel-01749003⟩



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