Research on new frequency convesion crystal BABF for vacuum ultraviolet light generation

我们发现了一种新的非线性光学（NLO）铝硼酸盐BaAlBO_3F_2 （BABF）晶体。用4轴x射线衍射对其结构进行了表征。材料BABF在空间群P6^^中结晶，a = 4.8879(6) Å， c = 9.403(1) Å， Z = 2。BABF结构是产生较大SHG系数、宽透明区域和适度双折射的理想结构模型。BABF的结构与KBe_2BO_3F_2 （KBBF）相似，但其组成中不含有毒元素。BABF晶体比KBBF晶体更容易生长，BABF晶体的生长周期也比其他非线性硼酸盐晶体短。BABF晶体可以生长尺寸为15 × 15 × 3.5mm^3。BABF晶体具有良好的化学性能、力学性能和光学性能，但晶体的质量有待提高，这方面的工作正在进行中。我们获得了一个透明的BABF晶体，并对其线性和非线性光学特性进行了测量。BABF的紫外吸收边很短（165nm）。BABF的粉末二次谐波产生效率（SHG）是KH_2PO_4 （KDP）的2倍左右。计算d_<11>(0.165pm/V)和d_<22> (1.32pm/V)。Type-1 SHG d_<eff>比LBO高约28%，Type-1 THG d_<eff>比LBO高31%。这表明，BABF是一个极好的候选频率混频到紫外线。

We have discovered a new nonlinear optical (NLO) alumino-borate BaAlBO_3F_2 (BABF) crystal. Its structure has been characterized by 4-axis X-ray diffraction. BABF, the material, crystallizes in the space group P6^^with a = 4.8879(6) Å, c = 9.403(1) Å and Z = 2. BABF structure is an ideal structural model for producing larger SHG coefficients, wide transparent region and moderate birefringence. BABF has a structure similar to that of KBe_2BO_3F_2 (KBBF), but does not contain toxic elements in its composition. BABF crystal is easier grown than KBBF and the growth period of BABF are relative shorter than other nonlinear borate crystals. BABF crystal can be grown with dimensions of 15 x15 x 3.5mm^3. BABF crystal possesses good chemical and mechanical and optical properties, but the quality of BABF crystal needs to be improved and the effort in this direction is underway. We have obtained a transparent BABF crystal for the measurements of its linear and nonlinear optical properties. The UV absorption edge of BABF s very short (165nm). BABF was found to have powder second harmonic generation (SHG) efficiency about twice than that of KH_2PO_4 (KDP). The d_<11>(0.165pm/V) and d_<22> (1.32pm/V) were calculated. Type-1 SHG d_<eff> is about 28% higher than that of LBO and Type-1 THG d_<eff> is 31% higher than that of LBO. It exhibits that BABF is an excellent candidate for frequency mixing into the ultraviolet.