Electro-Optic Property of Mg²⁺/Er³⁺-Codoped LiNbO₃ Crystal: Mg²⁺ Concentration Threshold Effect

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• 作者：Wan-Ying Du ; Zi-Bo Zhang ; Shuai Ren ; Wing-Han Wong ; Dao-Yin Yu ; Edwin Yue-Bun Pun and De-Long Zhang
• 刊名：Journal of the American Ceramic Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：100
• 期：1
• 页码：286-292
• 全文大小：737K
• ISSN：1551-2916

文摘

A series of Mg²⁺/Er³⁺-codoped congruent LiNbO₃ crystals were grown by Czochralski method from the growth melts containing 0.5 mol% Er₂O₃ while varied MgO content from 0.0 to 7.0 mol%. The unclamped electro-optic coefficients γ₁₃ and γ₃₃ of these crystals were measured by Mach–Zehnder interferometry. Two different voltage-applying schemes were adopted: one is the DC voltage applied to the crystal via Al films coated onto crystal surfaces and another is via a pair of external Cu slab electrodes. The coefficients measured by the two schemes show similar strong dependence on Mg²⁺ concentration. The dependence is non-monotonous, dramatic, and unusual, and reveals the features of two Mg²⁺ concentration thresholds of optical damage: one in the Mg²⁺ concentration range of 1.2–2.0 mol% (in crystal) and another in 4.5–5.0 mol%. Around the threshold the electro-optic coefficient decreases abruptly at first and then recovers quickly, and the coefficient drops by >20% (12%) at the first (second) threshold, which exceeds the error 3% considerably. The dramatic behavior is qualitatively explained on the basis of the EO coefficient model of LiNbO₃ and the defect structure model for Mg²⁺-doped LiNbO₃.