Growth by LHPG, Structure and Spectroscopy of Nd3+-Doped Ba2NaNb5O15 Nonlinear Single-Crystal Fibres |
| G. Foulon, M. Ferriol, A. Brenier, M.T. Cohen-Adad and G. Boulon Laboratoire de Physico-Chimie des Matériaux Luminescents, Unité Mixte de Recherche C.N.R.S. n° 5620, Université Claude Bernard Lyon I, Bât. 205, 43, bd. du 11 Novembre 1918, 69622-Villeurbanne, Cédex, France |
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| The renewal of the second order nonlinear crystals is very strong in laser materials optics. We are involved in the search for new systems based upon highly nonlinear niobate crystal family. Among these crystals, Ba2NaNb5O15 is characterized by the highest nonlinear parameters but, unfortunately, it is difficult to grow crackless samples. The obtention of good quality and crackless Ba2NaNb5O15 single crystals doped with different concentrations of Nd2O3 is reported. The crystals were grown as monocrystalline fibres by the laser heated pedestal growth technique. A new determination of the crystallographic structure of Ba2NaNb5O15 has been performed. The structure of fibres doped with 1 at.% Nd3+ was found orthorhombic with the new space group Pba2 instead of Cmm2. The well-known twinning of Ba2NaNb5O15 due to the exchange of the a and b axes of the unit cell, which disturbs the optical properties, decreases as the Nd3+ content of the fibre increases. Above 3%Nd3+ ions, such monocrystalline fibres were found to be of tetragonal structure. Low temperature spectroscopy reveals that Nd3+ ions substitute probably both Ba2+ and Na+ ions. The stimulated emission cross-section near 1060 nm of the 4F3/2 → 4I11/2 channel and its branching ratios are determined with the help of Judd-Ofelt analysis. This work shows that b-axis grown monocrystalline fibres are potentially self-doubling laser materials. |
| DOI: 10.12693/APhysPolA.90.63 PACS numbers: 61.66.Fn, 78.20.-e |