高功率窄线宽光纤激光的研究进展与发展趋势

高功率窄线宽光纤激光器具有光束质量好、结构紧凑等优点，在相干合成、光谱合成以及非线性频率变换等领域具有广泛的应用前景，基于窄线宽光纤激光相干合成、光谱合成的激光系统性能指标已经超越单束激光的最高性能，基于窄线宽光纤激光非线性频率变换的激光也实现了同类波段激光的最高性能。分析窄线宽光纤激光功率提升同时保持光束质量过程中产生的物理机制和面临的技术挑战，详细介绍学校课题组在高功率窄线宽光纤激光方面取得的代表性成果，特别是高光束质量的7 kW级非线偏振窄线宽激光和5 kW级线偏振窄线宽激光，不仅是同类激光的最高功率值，也逼近了同等条件下非窄线宽光纤激光的功率极限。根据近年来理论研究和技术攻关结果，结合国内外研究现状，对高功率窄线宽光纤激光未来几个发展趋势进行预判。

High-power narrow linewidth fiber laser: progress and prospect

High power narrow linewidth fiber lasers have a wide application prospect in the fields of coherent beam combining, spectral beam combining and nonlinear frequency conversion due to the inherent characteristic of high beam quality and structural compactness. Laser system indices based on coherent beam combining and spectral beam combining of narrow linewidth fiber laser have surpassed the best performance of single laser beam, and lasers based on nonlinear frequency conversion of narrow linewidth fiber laser have achieved the highest output properties of the counterparts with same wavelength region. This work has systematically analyzed the underlying physical mechanism and emerging technical challenges of narrow linewidth fiber laser power scaling without beam quality deterioration. Furthermore, it introduced representative achievements of the high power narrow linewidth fiber laser realized by our research group in detail, especially 7 kW level non-polarization-maintained narrow linewidth fiber laser and 5 kW level linearly-polarized narrow linewidth fiber laser, which have also approached power scaling capability limit of non-narrow linewidth counterparts at the same conditions. According to recent theoretical and key technical tackling results, we have anticipated the development tendency of high power narrow linewidth fiber laser on the basis of the current status at home and abroad.