Abstract LBO crystal up to 192 × 130 × 89 mm3 in size and 2327 g in weight has been grown by TSSG method and cut into an optical element with a size of 100 mm × 100 mm × 17 mm for critically phase-matched type I (θ = 90°, O = 13.85°). Near phase-matching direction growth was introduced to promote yield of the final large aperture LBO elements greatly from the limited mass of crystal. Take into consideration of crystallographic symmetry, the linear thermal expansion coefficients and crystal growth habit, LBO grown along [1 0 0] direction was proved to be the best choice to produce large element which meet the demands of high power OPCPA schemes. The grown LBO crystal possesses high optical quality, and shows no evidence that crystal growth modifications have detrimental influence on the crystal property. The laser-induced damage threshold (LIDT) at λ = 1064 nm and τ = 5 ns is 42 J/cm2 for 1-on-1 type tests. Absorption at 1064 nm has been found to be 10–20 ppm/cm at 1064 nm). Especially, the optical homogeneity reached 1.9 × 10−7 cm−1 in full aperture for the optical elements mentioned above, to the best of our knowledge, the highest optical homogeneity in borate crystals. This extremely high optical homogeneity, large aperture optical element of LBO is more favorable in the high power laser schemes.

中文翻译：

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应用于大功率OPCPA方案的大孔径LBO晶体的生长

摘要 用 TSSG 方法生长了尺寸为 192 × 130 × 89 mm3 和重量为 2327 g 的 LBO 晶体，并切割成尺寸为 100 mm × 100 mm × 17 mm 的光学元件，用于临界相位匹配 I 型（ θ = 90°，O = 13.85°）。引入近相位匹配方向生长，以从有限质量的晶体中大大提高最终大孔径 LBO 元件的产量。考虑到晶体对称性、线性热膨胀系数和晶体生长习性，证明沿 [1 0 0] 方向生长的 LBO 是生产满足高功率 OPCPA 方案要求的大元件的最佳选择。生长的 LBO 晶体具有高光学质量，并且没有证据表明晶体生长修改对晶体性质有不利影响。λ = 1064 nm 和 τ = 5 ns 的激光诱导损伤阈值 (LIDT) 为 42 J/cm2，用于 1 对 1 类型测试。已发现在 1064 nm 处的吸收为 10-20 ppm/cm（在 1064 nm 处）。特别是，上述光学元件在全孔径下的光学均匀性达到了 1.9 × 10−7 cm−1，据我们所知，这是硼酸盐晶体中最高的光学均匀性。LBO 的这种极高光学均匀性、大孔径光学元件在高功率激光方案中更为有利。