Matériaux doubleurs de fréquence (verres et vitrocéramiques à base d'oxyde de tellure - élaboration et caratérisation)

Des études récentes ont montré que les verres à base d'oxyde de tellure présentent des indices non linéaires élevés et que leurs performances sont renforcées, entre autres, par l'ajout d'oxyde de métaux de transition, faisant de ces matériaux des candidats potentiels à des applications "tout optiques" dans le domaine des télécommunications. La découverte d'une génération de seconde harmonique dans les verres pourrait alors favoriser le développement de ces matériaux pour l'intégration dans des systèmes optiques. Dans ce cadre, nous nous sommes inte ressés à l'élaboration et aux caractérisations physico-chimiques (structurales et optiques) des verres et vitrocéramiques de composition molaire 84,15% TeO2 14,85% WO3 2% SbO1,5. Cette composition était particulièrement intéressante pour cette étude puisqu'il a été possible de faire cristalliser des particules de la phase TeO2 g non centrosymétrique et ayant démontrée des propriétés de doublage de fréquence. Après optimisation des conditions de poling thermique, une forte susceptibilité non linéaire d'ordre deux a été mesurée au sein des verres et vitrocéramiques étudiés. Parallèlement, une étude visant à expliquer l'origine de la non linéarité de second ordre au sein de ces matériaux polés, a été entreprise par spectroscopie Raman et microsonde électroniqueLIMOGES-BU Sciences (870852109) / SudocSudocFranceF

All-optical poling of Tellurite glasses doped with heavy metal oxides

International audienc

Second harmonic generation of thermally poled tungsten tellurite glass

Second harmonic signals have been successfully generated for thermally poled glasses with 85%TeO2- 15%WO3 molar composition. Thermal poling was undertaken at various temperatures and heating times (voltage: 4.5 kV, sample thickness: 500 lm). The second harmonic generation (SHG) of the poled glasses was analysed using the Maker fringes technique. After optimisation of the poling conditions (T = 280 C, t = 1 h, 2 h), high v(2) values, up to 1.5 pm/V, were obtained. It was demonstrated that thermal poling has generated optically nonlinear zones at the anode side. The thickness of the SHG active layer was thin, lower than 20 lm. Two complementary hypothesis have been proposed to explain the origin of the second- order nonlinearity property of this tellurite glass: (i) a reorientation of the TeO4 glass structural entities under electric field and (ii) the formation of an anodic depletion region of sodium ions

Second order nonlinearity induced by thermal or optical poling in tellurite glasses

International audienc

Second harmonic generation in poled tungsten tellurite glasses

Second harmonic signals have been successfully generated in thermally poled 85%TeO2–15%WO3 glasses. Thermal poling of these glasses was undertaken at various temperatures and heating times using a voltage of 4·5 kV. The sample thickness was 500 mum. Second harmonic generation (SHG) in the poled glasses was analysed using the Maker fringes technique. After optimisation of the poling conditions (T=280°C, t=1 h), high chi(2) values (about 1·6 pm/V) were obtained. It was demonstrated that this thermal poling treatment has generated optically nonlinear zones on the anodic surface. The thickness of the surface layer given a SHG was thin (5·22 mum), as classically observed with tellurite glasses. The possible reorientation, under electric field, of the glass structural entities could be the origin of such second order nonlinear properties

Formation domain and characterization of new glasses within the Tl2O–TiO2–TeO2 system

International audienceA glass-forming domain is found and studied within the Tl2O–TiO2–TeO2 system. Linear and non-linear optical, thermal and mechanical characteristics were measured and/or theoretically estimated for relevant glasses, and found to be very promising for applications in non-linear optical designs. The chemical, lattice-dynamical and structural effects of the Tl2O and TiO2 modifiers are discussed by using the Raman spectroscopy data. It was concluded that the former modifier favours the non-linear optical properties of the glasses, whereas the latter improves their thermal and mechanical stabilities