热透镜效应对Er^(3+),Yb^(3+)∶glass激光器输出能量的影响  

Influence of Thermal Lens Effect on Output Energy of Er^(3+),Yb^(3+)∶Glass Laser

作　　者：宋庆坤 李海兵[1] 董永军[3] 何冬兵[1] 李顺光[1] 冯素雅[1] 王旭成 孔政伟 陈亮 阳求柏 Song Qingkun;Li Haibing;Dong Yongjun;He Dongbing;Li Shunguang;Feng Suya;Wang Xucheng;Kong Zhengwei;Chen Liang;Yang Qiubai(Key Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics,Ch inese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory for High Laser Field Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shcuighai 201800,China;Shanghai Daheng Optics and Fine Mechanics Co.,Ltd.,Shanghai 201800,China)

机构地区：[1]中国科学院上海光学精密机械研究所高功率激光单元技术实验室,上海201800 [2]中国科学院大学,北京100049 [3]中国科学院上海光学精密机械研究所强场激光物理国家重点实验室,上海201800 [4]上海大恒光学精密机械有限公司,上海201800

出　　处：《中国激光》2021年第17期17-24,共8页Chinese Journal of Lasers

基　　金：国家重点研发计划(2020YFB1805900)。

摘　　要：通过实验和理论相结合的方式,从热透镜效应角度研究了Er^(3+),Yb^(3+)∶glass在激光二极管(LD)端面抽运条件下的激光输出能量,建立起LD抽运重复频率、Er^(3+),Yb^(3+)∶glass热光系数与空腔运转斜率效率、调Q输出脉冲能量之间的关系。采用平凹腔结构,并以Co^(2+)∶MgAl_(2)O_(4)作为调Q开关,设计了LD端面抽运被动调Q激光器,实验结果发现,当热焦距大于前腔面光斑半径最小值对应的热焦距时,空腔运转斜率效率与材料的热光系数呈负相关,调Q输出脉冲能量与热光系数及抽运重复频率均呈负相关。基于理论研究,通过热焦距公式、稳定谐振腔的矩阵计算法以及被动调Q的速率方程进行数值模拟,解释并验证上述实验现象。结果显示,可通过降低抽运重复频率和选择低热光系数的Er^(3+),Yb^(3+)∶glass等方式降低热透镜效应实现高脉冲能量的输出。Objective Since Er^(3+),Yb^(3+)∶glass is used in laser diodes(LD)pumped lasers,several studies on thermal properties of Er^(3+),Yb^(3+)∶glass have been reported.However,there are still few related reports on the effect of pumping repetition frequency and the material thermo-optic coefficient on output energy.The pumping repetition frequency of LD and thermo-optic coefficient of Er^(3+),Yb^(3+)∶glass affect the thermal focal length and ultimately change the output energy of the Er^(3+),Yb^(3+)∶glass laser.Thus,in this study,we analyze the effect of pumping repetition frequency and the thermo-optic coefficient on output energy to guide material selection and output energy analysis for the endpumped high output energy Er^(3+),Yb^(3+)∶glass laser.Methods In this paper,we design a passively Q-switched laser with LD end-pumped to measure output energy using aplano-concave cavity structure and Co^(2+)∶MgAl_(2)O_(4) as the Q-switching crystal(Fig.1).The measuring thermal focal length experiment is based on the critical cavity method and uses a flat-flat cavity to measure the thermal focal length.In the measurement of slope efficiency,the variation of the output energy with pumping power is measured without Co^(2+)∶MgAl_(2)O_(4) in Fig.1under the same pumping conditions.Additionally,the thermal focal length formula,the matrix calculation method of the stable cavity,and the rate equation are used to analyze the phenomena in the above experiments.Results and Discussions In a passively Q-switched LD end-pumped laser,we obtained that the output pulse energy of EY1,EY2,and EY3decreases from 417,401,and 378μJ to 356,337,and 329μJ as the pumping repetition frequency increases from 10Hz to 28Hz(Fig.2).First,we verified the phenomenon that the thermal focal length decreases with increasing pumping repetition frequency theoretically and experimentally to analyze the above phenomenon.Second,by numerical simulation of the resonator,it is found that in the plane-concave cavity,the beam radius of the front surface of th

关 键 词：激光器 热透镜效应 输出能量 Er^(3+) Yb^(3+)∶glass 抽运重复频率 热光系数 

分 类 号：TN284.1[电子电信—物理电子学]