摘要
铌酸镓镧晶体(La_(3)Ga_(5.5)Nb_(0.5)O_(14),LGN)作为重要的中红外(2~20μm)非线性光学材料,具有宽的光谱透过范围(0.28~7.40μm)、大的二阶非线性系数(d11=(3.0±0.1)pm/V)及高的激光损伤阈值(>1.41 GW/cm^(2)@1064 nm),成为高功率中红外激光系统急需的优异晶体材料。本文总结了LGN晶体的结构特性、大尺寸生长技术、性能表征以及激光应用的研究进展。针对晶体生长过程中的热应力开裂与组分挥发难题,通过优化温场梯度、改善生长参数,成功制备直径80 mm大尺寸高质量单晶,为目前国际上尺寸最大的光学级LGN单晶。首次提出通过组分调控实现双折射色散与非线性系数的协同优化策略,开发出La_(3)(Nb_(1-x)Tax)_(0.5)Ga_(5.5)O_(14)(LGNTx)系列固溶体单晶,极大提升了有效非线性系数。利用LGN晶体差频产生技术实现了4.4~5.7μm中红外输出,而LGNTx混晶则将差频输出波长进一步扩展至6.84μm,这是目前氧化物晶体连续调谐输出的最长差频产生波长。上述研究结果为未来新型中红外非线性光学材料设计以及LGN晶体的规模化使用提供了重要的理论依据和应用前景。
As an important mid-infrared(at 2-20μm)nonlinear optical material,La_(3)Ga_(5.5)Nb_(0.5)O_(14)(LGN)crystal has a wide spectral transmission range(at 0.28-7.40μm),large second-order nonlinear coefficients(d11=3.0±0.1 pm/V),and high laser damage thresholds(>1.41 GW/cm^(2)@1064 nm),which makes it an excellent crystal material for high-power mid-infrared laser systems.In this review,we systematically summarize the structural properties of the LGN crystal,the large-size growth technology,the performance characterization,and the research progress of laser applications.To solve some problems of thermal stress cracking and volatilization of components during the growth process,a large-size and high-quality single crystal with a diameter of 80 mm is prepared via optimizing the temperature gradient and improving the growth parameters.Also we propose a synergistic optimization strategy of birefringent dispersion and nonlinear coefficient through component modulation,and develop La_(3)(Nb_(1-x)Tax)_(0.5)Ga_(5.5)O_(14)(LGNTx)series of solid-solution single crystals,greatly improving the effective nonlinear coefficient.The LGN crystal has 4.4-5.7μm mid-infrared output using the difference frequency generation technique,and the LGNTx hybrid crystals can extend the difference frequency output wavelength to 6.84μm,which is the longest wavelength for the continuous tuning output of oxide crystals.The results above provide an important theoretical basis and application prospect for designing new mid-infrared nonlinear optical materials and the large-scale use of LGN crystal in the future.Summary and prospects This review represents a comprehensive and in-depth summary of the La_(3)Ga_(5.5)Nb_(0.5)O_(14)(LGN)crystal,covering important achievements in various key aspects,such as crystal structure and basic properties,large-size growth technology,nonlinear optical properties,mid-infrared nonlinear optical properties,and applications.In terms of large-size crystal growth,some technical problems of thermal stress cracking and component segregation during the growth of LGN are solved,and the preparation of large-size single crystals with the diameters of 60-80 mm is stablized.Meanwhile,the LGN crystal has nonlinear optical properties and applications,which provides a support for the development of high-power mid-infrared laser systems.In the future,we need to optimize the crystal growth to obtain more accurate temperature regulation,further shorten the growth cycle,improve the growth efficiency,reduce the internal defects,and improve the annealing process,to obtain larger size(≥4 inches)high-quality LGN crystal,providing a better material base for high-performance mid-infrared laser.In addition,it is also necessary to investigate the performance regulation mechanism of LGN hybrid crystals in depth,and further optimize their nonlinear optical properties via utilizing elemental doping and structural fine-tuning,such as improving the nonlinear coefficient and broadening the gain bandwidth,to provide nonlinear optics crystals with excellent performances for the realization of high-power OPCPA applications.Developing mid-infrared laser sources and optoelectronic devices can meet a demand for mid-infrared wavelength lasers in biomedicine,environmental monitoring,national defense,security,and etc.
作者
顾洪旭
韩金锋
路大治
梁飞
武奎
于浩海
张怀金
GU Hongxu;HAN Jinfeng;LU Dazhi;LIANG Fei;WU Kui;YU Haohai;ZHANG Huaijin(State Key Laboratory of Crystal Materials,School of Crystal Materials,Shandong University,Jinan 250100,China)
出处
《硅酸盐学报》
北大核心
2025年第12期3484-3493,共10页
Journal of The Chinese Ceramic Society
基金
国家重点研发计划(2023YFB3610603)
国家自然科学基金(52272004)。
关键词
铌酸镓镧
提拉法
晶体生长
非线性光学
中红外激光
nanthanum gallium niobate
Czochralski method
crystal growth
nonlinear optics
mid-infrared lasers
