YCOB晶体生长与激光倍频性能研究

Research on Growth and Second-Harmonic Generation of YCOB Crystals

坩埚下降法沿＜０１０＞和＜００１＞方向生长了直径达到２５ｍｍ的完整透明的Ｃａ４ＹＯ（ＢＯ３）３ （ＹＣＯＢ）晶体．化学腐蚀结果表明，所生长晶体无孪晶或亚晶界等缺陷，晶体尾部的位错密度 不超过１８００／ｃｍ２测量了ＹＣＯＢ的透射光谱，其截止波长为２００ｎｍ进行了ＹＣＯＢ晶体对 Ｎｄ：ＹＡＧ激光的二次倍频实验．通过与ＫＤＰ晶体对比，计算出ＹＣＯＢ晶体的有效非线性系数 在Ⅰ型相位匹配方向（θ，φ）＝（６６．３°，１４３．５°）和（６５．９°，３６．５°）上分别为１．４５ｐｍ／Ｖ和０．９１ｐｍ／Ｖ； 大于ＫＤＰ和 ＬＢＯ晶体．在脉冲宽度１０ｎｓ的 Ｎｄ：ＹＡＧ激光单脉冲辐射下ＹＣＯＢ晶体出现体 损伤的激光损伤阈值不低于８５ＧＷ／ｃｍ２．

Crack-free and transparent Ca4YO(BO3)(3) (YCOB) crystals with 25 mm diameter were grown by the vertical Bridgman method in <010> and <001> directions. The results of chemical etching indicate that there are no sub-boundaries or twins in the crystal, and the density of dislocations observed at top region of a crystal is less than 1800/cm(2). The measured transmission spectrum shows that the crystal has wide transmission range with absorption edge at 200nm. The SHG of a Nd:YAG laser was performed for YCOB crystals in comparison with KDP crystal, the effective nonlinear coefficients (d(eff)) of YCOB in type I phase matching directions of (theta, phi)=(66.3degrees, 143.5degrees) and (65.9degrees, 36.5degrees) were estimated to be 1.45pm/V and 091pm/V respectively. The bulk damage threshold was observed as 85G W/cm for single pulse of a Nd:YAG laser with 10 pulse duration.