用于光纤激光泵浦的透射光栅外腔反馈光谱合束高亮度半导体激光源研究

To solve the problem of low brightness and instable spectrum of the current fiber laser pumping sources, as the purpose of the project, it is of a great significance to develop high power diode laser sources with the characteristic of high brightness (>100MW*cm-2*sr-1) and high spectrum stability (<0.01nm/℃) for propelling the development of high-end fiber lasers. A novel diode laser source structure with a narrow spectrum based on the technology of transmission grating-external cavity feedback spectral beam combining (T-SBC) is designed and developed. With meeting the requirements of optical pumping spectrum, the brightness of the diode laser source increased nearly 100 times. The structure technology of T-SBC is researched rigorously, and the new methods of increasing the brightness of the SBC source, improving the reliability and compressing the spectrum width are further explored. The key points about how to improve spectral beam combining of multi-laser units and how to narrow and stabilize the output spectrum are solved. Making 976nm diode laser sources as the breakthrough point, the technology of T-SBC would be expanded to other wavelengths, improving the performance of different doped fiber lasers. Meanwhile, as the solution of the key technology of improving the beam quality of high power diode laser sources, the technical reserves for a new generation high brightness laser source with high efficiency and energy saving will be provided, and the pace of diode laser sources as the direct sources applied to the industry and defense will be accelerated.

针对当前光纤激光泵浦源亮度不高、光谱漂移大的问题，项目以研制高亮度（>100 MW*cm-2*sr-1）、高光谱稳定（<0.01nm/℃）的高功率半导体激光源为目标，对于发展高端光纤激光器具有重要意义。提出并设计了一种新型的基于透射光栅外腔反馈光谱合束技术并能窄化光谱的半导体激光源结构，在满足泵浦光谱要求条件下，激光亮度提高近100倍。系统开展基于透射光栅外腔光谱合束技术的研究，探索如何提高合束光源激光亮度、提升光源可靠性和压缩输出谱宽的新方法，解决多激光单元光谱锁定、多激光单元高效光谱合束、输出光谱稳定及窄化的关键技术。以976nm半导体激光源为突破口，通过项目开展，将光栅外腔光谱合束技术拓展至其他波长，提升不同掺杂光纤激光器性能。同时解决半导体激光光束质量提升的核心设计和研制技术，为新一代高效节能、高亮度激光光源提供技术储备，加速半导体激光源作为直接光源应用于加工及国防领域的步伐。

针对当前光纤激光泵浦源亮度不高、光谱漂移大的问题，项目以研制高亮度（>100 MW*cm-2*sr-1）、高光谱稳定（<0.01nm/℃）的高功率半导体激光源为目标，提出一种基于衍射光栅外腔反馈光谱合束并能窄化光谱的新方法，并设计了半导体激光源外腔反馈结构，通过在谐振腔内引入中继成像、长焦变换透镜、腔内选模等结构，提高了合束光源激光亮度，压缩了输出光谱谱宽，解决了多激光单元光谱锁定、多激光单元高效光谱合束、输出光谱稳定及窄化的关键技术，研制出中心激光波长975.9nm，激光谱宽3.56nm，整体光谱漂移0.0025nm/℃，连续功率244W、光束质量4.498mm•mrad，激光亮度122MW/cm2/sr的半导体激光光源，满足光纤激光器泵浦需求，发表论文5篇，申请发明专利5项，达到项目既定指标。通过该项目的实施，为改善半导体激光光束质量和光谱特性找到一条有效途径，为新一代高效节能、高亮度激光光源提供技术储备，加速半导体激光源作为直接光源应用于加工及国防领域的步伐。