400mm口径4×2组合式片状放大器动态漂移  

Dynamic Drift of Laser in 4 × 2 Assembled Slab Amplifier with 400 mm Aperture

作　　者：王振国[1] 陈林[1] 薛峤[1] 吴文龙[1] 刘建国[1] 刘勇[1] 王琳[1] Wang Zhenguo;Chen lin;Xue Qiao;Wu Wenlong;Liu Jianguo;Liu Yong;Wang Lin(Laser Fusion Research Center,China Academy of Engineering Physics,Mianyang 621900,Sichuan,China)

机构地区：[1]中国工程物理研究院激光聚变研究中心,四川绵阳621900

出　　处：《中国激光》2022年第9期79-87,共9页Chinese Journal of Lasers

摘　　要：在大口径片状放大器系统中,非对称泵浦导致经过增益介质的激光束发生动态漂移。研究了泵浦场对称性(用钕玻璃长度方向中心左右两侧的泵浦能量比值表征)对光束动态漂移的影响,建立了理论模型并开展了实验研究。实验结果表明,当增益介质泵浦场的对称性约为1.038∶1时,泵浦致光束的动态波前倾斜值约为0.98λ(波长为1053nm的激光经过六张钕玻璃片后的累积波前畸变量,λ=1053nm),375mm光束口径下激光单次经过单钕玻璃片的动态漂移角度约为0.32μrad,与理论模型吻合较好。激光装置全链路的分析结果表明,在基于反转器的四程放大构型中,累积的动态波前倾斜峰谷值约为2.78λ,漂移比例(漂移量与30倍衍射极限下的小孔直径的比值)约为2.14%。Objective The research of inertial confinement fusion(ICF)has been a hot spot in international research in recent decades.The slap amplifier provides more than 99%of the energy for the entire laser device and is the heart.However,during laser amplification,asymmetric pumping causes uneven heating of the gain medium,resulting in a drift in the laser propagation direction through the neodymium glass sheet,that is,an angular drift of the laser.The accurate evaluation of the angular drift influences the multi-pass design of the amplifier,which ensures the main laser passes through the spatial filter aperture smoothly and provides a design basis for the filter aperture size and the working mode of the deformable mirror compensation.Starting from the influence of the pump on the medium,we have independently developed a set of design models,hoping to design the amplifier more accurately based on domestic components and obtain a smaller and more accurate angular drift,which is helpful to the better design of chip amplifiers.Methods A theoretical model is established as shown in Fig.2.We first use the pump configuration as the input condition to obtain the pump field distribution on the gain medium through three-dimensional ray tracing,and then obtain the heat distribution on the gain medium.On the one hand,the thermal distribution is first combined with the boundary conditions of the clamping method to obtain the stress distribution on the gain medium,and then the surface shape distribution is obtained.On the other hand,the heat distribution and stress distribution jointly determine the distribution of refractive index changes on the gain medium.These two together determine the angular drift of the transmitted laser beam.This article uses the model to design and manufacture the amplifier.A set of three pieces of 400 mm diameter 4x2 combined chip amplifiers is developed.In the height direction of the amplifier,the stack of four neodymium glass plates forms four laser apertures,and there are two laser apertures in the widt

关 键 词：激光器 片状放大器 泵浦对称性 动态漂移 模拟计算 实验研究 

分 类 号：O140[理学—数学]