紫外硼酸-磷酸盐非线性光学晶体Ba3(ZnB5O10)PO4生长及355nm激光输出器件研究

UV laser has wide application prospects in the fields, such as lithography, photoelectron spectroscopy, precision machining, etc. UV nonlinear optical crystal (NLO) is the core material of solid-state laser for producing short wavelength laser. Borates and phosphates have abundant structure chemistry, large second harmonic generation (SHG) response and short ultraviolet cut-off edge. They are ideal choice for the design of new UV NLO materials. In applicant’s previous study, a new borate-phosphate NLO material Ba3(ZnB5O10)PO4 (BZBP) has been successfully designed and synthesized by combining borate group and phosphate group in a material. This material has a large SHG response (4×KDP) and a short UV cut-off edge (180 nm). The primary research indicates that BZBP is a promising NLO crystal for 355 nm laser output. In this research, we will optimize the parameters of BZBP crystal growth and overcome the high viscosity of BZBP melt, which may lead to slow crystal growth, inclusions and clouds, and grow the high quality of BZBP crystal with a size not less than 40×40×20 mm3. With the grown high quality crystal, we will process the crystal devices and measure the NLO coefficients, walk-off angle, laser damage threshold, and refraction of rate of temperature dispersion relation. These researches will not only provide a new alternative material for 355 nm laser output, but it is also helpful for the crystal growth in other system with a high viscosity.

紫外激光在光刻、光电子能谱、仪器精密加工等领域拥有广泛应用前景，而紫外非线性光学晶体是获得紫外激光的关键材料。硼酸盐和磷酸盐具有丰富的结构化学、大倍频效应和短紫外截止边，是紫外非线性光学材料设计的理想选择。申请人前期将硼酸盐与磷酸盐结合制备出倍频效应达4×KDP、紫外截止边为180nm的硼酸-磷酸盐Ba3(ZnB5O10)PO4(BZBP)，初步性能测试表明该晶体在355nm激光输出方面具有潜在应用前景。本项目拟采用顶部籽晶法生长BZBP晶体，重点解决晶体生长过程中由于高体系粘度导致的晶体生长缓慢，易产生包裹及云层等宏观缺陷，稳定生长出可供355nm固体激光器性能测试用40×40×20mm3高质量晶体，加工单晶器件，系统评估其在355nm激光输出应用中的非线性光学系数、走离角、激光损伤阈值及折射率温度色散关系，为355nm激光输出提供一种新的备选材料，同时为高粘度体系晶体生长提供技术借鉴。

项目实施过程中已通过顶部籽晶法生长了Ba3(ZnB5O10)PO4(BZBP)晶体，晶体尺寸达45×45×20mm3。该晶体结晶于正交空间群，其点群为mm2，BZBP有三个非零的非线性光学系数，根据实验要求，通过研磨抛光后加工通光面为(010)面尺寸为4.0×4.0×1.84mm3和通光面为(100)面尺寸为4.0×4.0×1.82mm3的晶片。基于上述晶片，对BZBP的非线性光学系数进行了Maker条纹测试，拟合了其非线性光学系数。同时结合BZBP的色散方程，对BZBP在Nd:YAG激光器的二倍频(532nm)和三倍频(355nm)激光输出方面性能进行了理论和实验研究。基于折射率测试结果计算了BZBP的走离角。基于Nd:YAG激光器测试了其激光损伤阈值达1.77GW/cm2(λ=1064nm，τ=10ns)。实验中也获得的其它系列硼磷酸盐，K3B4PO10、K2MB4PO10 (M=Rb/Cs)和NH4(B6PO10(OH)4)·H2O和LiNa4B2P3O13，其中LiNa4B2P3O13为非中心同成分的化合物，通过顶部籽晶法已生长14×14×12mm3的晶体，研究了系列中心对称的硼磷酸盐K3B4PO10、K2MB4PO10(M=Rb/Cs)和NH4(B6PO10(OH)4)·H2O化合物中，硼磷比对结构各项异性的影响规律。项目执行过程中产出论文18篇，申请中国发明专利2项。培养研究生4名。