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晶体BaAlBO_3F_2（BABF）。用四轴X射线衍射仪对其结构进行了表征。BABF是一种晶体，空间群为P6 ^^，a = 4.8879（6）<$，c = 9.403（1）<$，Z = 2。BABF结构是产生较大倍频系数、宽透明区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，但不含有毒元素。BABF晶体比KBBF晶体更容易生长，生长周期也比其他硼酸盐非线性晶体短。BABF晶体可以生长为15 × 15 × 3.5mm^3的尺寸。BABF晶体具有良好的化学、力学和光学性能，但其质量有待提高，目前这方面的研究工作正在进行中。我们获得了一个透明的BABF晶体，用于测量其线性和非线性光学性质。BABF的紫外吸收限很短（165 nm）。BABF的粉末倍频效率约为KH_2PO_4（KDP）的2倍。计算出d_<11>（0.165pm/V）和d_<22>（1.32pm/V）。1型SHG d_1<eff>比LBO高约28%，1型THG d_1<eff>比LBO高31%。这表明BABF是一种很好的紫外混频材料。

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.