Rare-earth doping, various post-growth heat treatments and aging effects on OH^? absorption in LiNbO₃ crystal

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• 作者：De-Long Zhang ; Wen-Zhu Zhang ; Jian Gao ; Ping-Rang Hua ; Bei Chen ; Edwin Yue-Bun Pun
• 关键词：Rare-earth-doped LN crystal ; OH&minus ; absorption ; Li-rich/Li-poor VTE ; Aging effect ; Thermal reduction ; Oxidation ; Optical materials ; Heat treatment ; Infrared spectroscopy (IR) ; Phonons ; Defects
• 刊名：Materials Chemistry and Physics
• 出版年：2012
• 出版时间：15 August, 2012
• 年：2012
• 卷：135
• 期：2-3
• 页码：416-424
• 全文大小：1404 K

文摘

Rare-earth-doping and various post-growth heat treatments effects on OH^? absorption in singly Er- and Yb-doped, doubly Er/Mg- and Er/Yb-doped LiNbO₃ crystals have been investigated. The OH^? absorption in the rare-earth-doped crystals shows definite anisotropy and is stronger in a Z-cut plate. Rare-earth-doping causes considerable OH^? absorption reduction. MgO-codoping induces additional reduction. Slight/heavy rare-earth-doping causes slight/considerable spectral shape change. Thermal reduction treatment causes OH^? absorption vanishing whether the crystal is originally congruent or near-stoichiometric. Further oxidation treatment renders the absorption reemerged. Li-rich vapor transport equilibration (VTE) treatment causes significant absorption decrease. For a slightly rare-earth-doped Li-rich VTE-treated crystal, its spectral feature is similar to that of the undoped near-stoichiometric crystal; for a heavily rare-earth-doped VTE-treated crystal, its spectral shape preserves the feature of the heavily rare-earth-doped as-grown crystal. For the Er/Mg-codoped crystal studied, the Li-rich VTE also induces an abrupt conversion of peaking position from 3483?cm^?1 to 3535?cm^?1. The absorption in the Li-rich VTE-treated crystals also reveals aging effects in spectral shape, peaking position and absorption intensity. Li-poor VTE induces significant absorption increase. In addition, the effect of OH^? presence on lifetime of Er³⁺ emission at 1.5?¦Ìm was also studied. The results show that the effect is small for the as-grown congruent crystals and slight for Li-rich VTE-treated ones.