高功率高光束质量级联泵浦掺镱光纤激光器研究进展  

Research Progress in Tandem-Pumped High-Power and High-Beam Quality Ytterbium-Doped Fiber Laser

作　　者：肖虎 李瑞显 吴函烁 黄良金 陈子伦 杨欢 闫志平 王蒙 潘志勇 王泽锋 周朴[1] 陈金宝[1,2] Xiao Hu;Li Ruixian;Wu Hanshuo;Huang Liangjin;Chen Zilun;Yang Huan;Yan Zhiping;Wang Meng;Pan Zhiyong;Wang Zefeng;Zhou Pu;Chen Jinbao(College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,Hunan,China;Nanhu Laser Laboratory,National University of Defense Technology,Changsha 410073,Hunan,China)

机构地区：[1]国防科技大学前沿交叉学科学院,湖南长沙410073 [2]国防科技大学南湖之光实验室,湖南长沙410073

出　　处：《光学学报》2023年第17期188-207,共20页Acta Optica Sinica

摘　　要：级联泵浦方案具有泵浦光亮度高、量子亏损小、光纤热负荷低、模式不稳定阈值高等优势,是获得高功率光纤激光的主要技术方案。目前,万瓦级高光束质量光纤激光的实现在非线性效应抑制和模式控制等方面遇到困难。本文介绍了国防科技大学近年来在高光束质量级联泵浦光纤激光器方面的研究进展,并对功率和光束质量进一步提升的可行途径进行了分析。Significance Compared with the laser diode(LD)-pumped scheme,the tandem-pumped scheme has the advantages of high pump brightness,small quantum defect,and low thermal load,making it the main technical solution for ultra-high power ytterbium-doped fiber lasers(YDFLs).Nevertheless,due to the weak absorption of Yb-ions at 1018 nm,it is necessary to enlarge the core diameter or increase the length of YDF to improve the total pump absorption,resulting in more severe nonlinear effects[mainly stimulated Raman scattering(SRS)]and transverse mode instability(TMI).Despite the 20 kW YDFLs have been obtained based on YDF with a core diameter of about 50μm and tandem-pumped scheme,the beam quality is poor for the lacking of efficient mode control.It is very challenging to maintain excellent beam quality with increasing power actually,due to the contradictions between the SRS and TMI suppression strategies.Although IPG photonics has announced a 10 kW single-mode YDFL tandem pumped by 1018 nm YDFLs as early as 2009,no other institutions have ever reported>5 kW YDFL with high beam quality(M^(2)<2)as of 2021.We presented the research progress on tandem-pumped YDFLs achieved by National University of Defense Technology in the past three years.Possible approaches to enhance power and beam quality were also discussed.Progress To balance high power and high beam quality,we proposed a backward/bidirectional tandem-pumped solution.Although backward/bidirectional pumping schemes are widely applied in LD-pumped laser systems,investigations on their technicalities in tandem-pumped YDFL are very rare in open publications.The primary reason is that in the tandempumped YDFL,the 1018 nm fiber laser which functions as the pump source,is highly susceptible to the signal light.Even a small proportion of signal light coupled into the 1018 nm fiber laser might cause significant power decline,even leading to the destruction of the 1018 nm laser.By optimizing the 1018 nm laser oscillator and the backward combiner,we successfully reduced the adverse

关 键 词：高功率光纤激光器 级联泵浦 受激拉曼散射 光束质量 

分 类 号：O436[机械工程—光学工程]