Accurately known energy level structure of the A＇∑u＋b3 IIu complex of states from a recent global de-perturbation of these states has enabled additional assignments of 140 perturbation facilitated infrared-infrared double resonance （PFIIDR） transitions to the 2^3△1g state from collisionally populated intermediate 1 ＋ A Eu levels. Together with the 221 previously observed 2^3△1g←A1∑u＋←X1∑g＋ Eu X Eg double resonance lines [J. Chem. Phys. 128, 204313 （2008）], molecular constants and the Rydberg-Klein-Rees potential energy curve of the 23△1g state have been recalculated （excluding 54 perturbed levels）. The centrifugal distortion constant has been determined and agrees well with the value calculated based on standard empirical formulas. The hyperfine structure of the 23△1g state, which has not resolved in our sub-Doppler excitation spectra of the 23△1g state, has been interpreted with a preliminary simulation.
基于国产光纤构建了直接抽运全光纤化主控振荡器功率放大器结构光纤激光器,放大级分别采用武汉烽火锐光科技有限公司和中国电子科技集团公司第四十六研究所提供的国产20/400μm掺镱双包层光纤作为增益光纤,通过全国产化放大级实现了3050和3092 W的1080 nm激光输出.放大级提取效率分别为67.3%和68.2%,光-光效率分别为63.0%和63.9%.据可查询资料,这是公开报道的直接抽运全光纤激光输出的最高水平,同时由于采用了国产光纤作为放大级增益光纤,表明国产光纤具备了3 k W级光纤激光器输出能力.通过国产光纤横截端面以及光纤熔接显微镜图像实验分析知,光纤制造工艺的不足是导致国产光纤激光器效率低的主要原因.继续改进光纤工艺,提升抽运功率,优化光纤长度,有望实现更高功率的全国产化光纤激光器输出.
