50W量级近衍射极限980nm波段光纤激光器实验研究  

Experimental Study on 50-W-Level Near-Diffraction-Limit Fiber Laser near 980 nm

作　　者：曹涧秋[1,2,3] 李昭德 陈毛妮 刘爱民 黄值河 王泽锋 陈金宝 Cao Jianqiu;Li Zhaode;Chen Maoni;Liu Aimin;Huang Zhihe;Wang Zefeng;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;State Key Laboratory of Pulsed Power Laser 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 [3]脉冲功率激光技术国家重点实验室,湖南长沙410073

出　　处：《光学学报》2024年第13期171-178,共8页Acta Optica Sinica

摘　　要：基于阶跃折射率双包层掺镱光纤,实现了50 W量级近衍射极限980 nm波段光纤激光器的实验验证。光纤激光器采用主振荡功率放大(MOPA)结构。实验结果表明:仅通过提升种子光的光束质量,不足以有效提升激光器的光束质量,同带放大自发辐射(ASE)也会对激光器的光束质量产生显著影响。通过优化掺镱光纤的长度,实现了同带ASE抑制的优化,在输出功率达到50 W量级的条件下,同带ASE的抑制比从16.6 dB提升到33.2 dB,输出光场的光束质量因子(M2)也由1.79提升至1.48。该实验揭示了同带ASE对于980 nm波段光纤激光器光束质量提升的影响,对于高亮度980 nm波段掺镱光纤激光器的研究具有指导意义。Objective High-brightness and high-power fiber lasers operating near 980 nm have important applications because they can not only be applied for pumping the ultrafast solid-state and fiber lasers but also generate the emission around 490 nm by frequency-doubling. However, it is difficult to achieve high-power near-diffraction-limited operation for the fiber laser operating near 980 nm. The main reason is that the large core-to-cladding area ratio(CCAR) of the active fiber is needed to suppress the amplified spontaneous emission(ASE) around 1030 nm. Although some micro-structured fibers have been designed for suppressing the ASE around 1030 nm and maintaining good beam quality, their difficult manufacturing and drawing processes limit the popularization of pertinent studies. Therefore, more studies have been carried out by using double-cladding Yb-doped fibers(DCYFs). However, the beam quality achieved by the DCYF is generally poor.Moreover, the strong in-band ASE is observed, but its effect on the beam quality is not clear. Therefore, in this paper, an experimental study is carried out to explore the effect of the in-band ASE on beam quality with the help of a 50-W-level master oscillator power amplifier(MOPA) fiber laser operating near 980 nm. It is also demonstrated that the suppression of in-band ASE can be improved by shortening the length of DCYF. We hope that our study can be helpful in designing the high-power near-diffraction-limited fiber laser near 980 nm with DCYF.Methods As shown in Fig. 1, the MOPA fiber laser consists of a seed oscillator and an all-fiber amplifier. Firstly, the seed oscillator was fabricated, and the output properties of seed light were measured. The effects of the mode field adapter(MFA) and filter on the beam quality of seed light were investigated. Then, the all-fiber amplifier was fabricated and tested with the seed light. The active fiber length was determined to be 0.56 m, so as to suppress the ASE around 1030 nm, and the output power, spectrum, and beam quality of the amplif

关 键 词：光纤激光器 掺镱光纤 放大自发辐射 光束质量 

分 类 号：TN248[电子电信—物理电子学]