基于掺镱棒状光纤的高功率大能量四路相干合成飞秒激光系统  

High-power high-energy four-channel fiber coherent beam combined system

作　　者：史卓 常洪祥 王栋梁 郭鸿宇 董自凯 杜志航 梁成斌 李灿 周朴[4] 魏志义[1,2,3] 常国庆 SHI Zhuo;CHANG Hongxiang;WANG Dongliang;GUO Hongyu;DONG Zikai;DU Zhihang;LIANG Chengbin;LI Can;ZHOU Pu;WEI Zhiyi;CHANG Guoqing(Key Laboratory of Optical Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,China)

机构地区：[1]中国科学院物理研究所,光物理重点实验室,北京100190 [2]中国科学院大学,北京100049 [3]松山湖材料实验室,东莞523808 [4]国防科技大学前沿交叉学科学院,长沙410073

出　　处：《物理学报》2025年第1期168-175,共8页Acta Physica Sinica

基　　金：中国科学院重点部署科研专项(批准号:PTYQ2022YZ0001);国家自然科学基金(批准号:62175255,62227822);国家重点研发计划(批准号:2021YFB3602602)资助的课题.

摘　　要：高平均功率(>500 W)、大脉冲能量(>1 mJ)飞秒光纤激光对包括阿秒光学在内的众多科研领域极为重要.受限于增益光纤较小的模场面积,多种非线性效应将从单根增益光纤放大产生的飞秒脉冲的能量限制在百微焦量级.平均功率和脉冲能量的进一步提升需要使用相干合成技术,将多路光纤的输出合成为一束.本文搭建了一套基于填充孔径相干合成的高功率大能量超快光纤激光系统,采用商用掺镱棒状光纤并利用随机并行梯度下降法实现四路放大器之间的相位锁定.在重复频率为1 MHz时,该相干合成系统输出平均功率为753 W,经过光栅对压缩后的平均功率为672 W,脉冲宽度为242 fs,对应的脉冲能量为0.67 mJ,系统具备良好的稳定性.降低重复频率至500 kHz,该系统输出压缩后的脉冲平均功率为534 W,脉冲宽度为247 fs,对应脉冲能量可达1.07 mJ.脉冲的平均功率和能量均可通过增加合成路数进一步提升,通过添加已着手研发的延迟和指向锁定系统,有望通过八路相干合成实现平均功率超过1 kW、脉冲能量超过2 mJ的飞秒脉冲输出.Ultrafast fiber laser sources with mJ-level pulse energy and kilo-watt average power are of particular importance for various science fields such as attosecond lasers.Currently,several large-scale facilities for attosecond lasers,including ELI-ALPS in Europe,SECUF in China,NeXUS in America and ALFA in Japan are under construction.High-performance femtosecond driven lasers are crucial for attosecond lasers and various ultrafast laser facilities.Fiber lasers have a large surface-to-volume ratio,which enables efficient cooling and is suitable for high average power amplification.However,due to small mode area of optical fibers,detrimental nonlinear optical effects such as self-phase modulation,four-wave mixing,and stimulated Raman scattering limit the peak power of pulse to hundreds of MW,corresponding to pulse energy of hundreds ofμJ for femtosecond pulses in large mode area rod-type fibers.In addition,the average power of fiber lasers is limited by transverse mode instability,which reduces the stability and quality of beams above a certain threshold.In rod-type fibers,the threshold is about 250 W.Neither average power nor pulse energy emitted by single fiber meets the requirement for attosecond laser generation.The average power and pulse energy can be further scaled by coherent beam combination,which involves splitting pulses caused by an frontend laser and recombining them after amplification.It is essential for coherent beam combination to maintain the coherence of pulse replicas,which usually involves high speed photodiode detectors,piezo-driven mirrors,and other electronics forming a feedback system to actively control the phase of all replicas.We present a high-energy high-power ultrafast fiber laser system by using filled-aperture coherent combination of four ytterbium-doped rod-type fiber amplifiers.The phase control is achieved by using stochastic parallel gradient descent method.The frontend includes a passively mode-locked Yb-fiber oscillator,a stretcher,a pulse picker,and three fiber pre-amplifiers,wh

关 键 词：超快光纤激光 高功率大能量 相干合成 

分 类 号：TN24[电子电信—物理电子学]