Growth, characterization and the fourth harmonic generation at 266 nm of K₂Al₂B₂O₇ crystals without UV absorptions and Na impurity

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• 作者：Yonggang Wang ; Lirong Wang ; Xin Gao ; Guiling Wang ; R.K. Li ; ^{rkli@mail.ipc.ac.cn} ; C.T. Chen
• 关键词：A1. UV absorption ; A2. Top seeded solution growth ; B1. Borates ; B2. Nonlinear optical crystal
• 刊名：Journal of Crystal Growth
• 出版年：2012
• 期刊代码：49_00220248
• 类别：ch
• 出版时间：1 June, 2012
• 卷：348
• 期：1
• 页码：1-4
• 文件大小：481 K

摘要

We utilize a combined technology to grow relatively pure K₂Al₂B₂O₇ crystals without sodium and UV absorptions aroused by Fe³⁺ ions. It is found that under reducing atmosphere, iron impurities can no longer substitute into the Al³⁺ sites in the crystal lattice. Thus, the as-grown crystals are free from the abnormal UV absorption from 200 nm to 300 nm. At the same time, KF flux prevents the inclusion of sodium into the crystal contrasted with the generally used NaF flux. Lattice parameters of the as-grown crystals were refined by powder X-ray diffraction and compared with those grown from NaF flux. Based on the measured refractive indices, new Sellmeier equations were derived from refractive index dispersion curves. Finally, FHG experiment of a QCW Nd:YAG laser at 266 nm demonstrated an output power of 440 mW, which is the highest record achieved in KABO crystal so far.