掺Yb3+新型晶体激光特性的研究
文献类型：学位论文
| 作者 | 许毅 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 梁晓燕 |
| 关键词 | Yb3+新型晶体 二极管泵浦 调谐 被动锁模 |
| 其他题名 | Research on the Laser Performance of the Novel Yb3+-doped Crystals |
| 中文摘要 | 随着900-980nm的高强度高亮度InGaAs二极管的迅速发展，掺Yb3+的激光材料越来越多地受到了人们的关注。相对于掺Nd3+的激光材料而言，Yb3+离子具有更长的上能级寿命，储能能力强。且掺Yb3+的激光材料仅有两个电子态：基态2F7/2和激发态2F5/2(两者的能量间隔约为10000cm-1)。由于在这个能级之上不存在任何其他激光态能级，所以可以避免上能级转换﹑激发态吸收和弛豫振荡等激光能量损耗而实现高效的激光运转。更为重要的是，Yb3+离子具有更宽的吸收和发射光谱，其吸收带在900～1000 nm范围，能与InGaAs半导体抽运源(870～1100 nm)有效耦合，且吸收带较宽，使得二极管泵浦不需要复杂的温度控制系统，而宽带发射光谱又使得掺Yb3+的激光材料更适合实现可调谐连续输出和超快激光运转。Yb3+的这些特点使得其在一些应用上明显优于掺Nd3+激光晶体，因此 Yb3+掺杂的激光材料有希望成为新一代二极管泵浦的全固态超快激光器的首选增益介质。 本论文中，对两种掺Yb3+新型晶体的激光特性进行了理论分析和创新性的实验研究。首先，我们研究了Yb:LSO晶体的激光特性，获得了高效，宽调谐范围的激光输出。为了更好地研究该晶体的锁模特性，之后，我们开展了基于SESAM被动锁模Nd:YVO4激光器的研究，实验中的连续﹑稳定锁模阈值与理论阈值基本吻合。在此基础上，我们进行了SESAM被动锁模Yb:GYSO激光器的研究，获得了稳定连续的锁模脉冲输出。Yb:GYSO晶体高效﹑宽调谐的激光特性说明了Yb:GYSO晶体适用于激光锁模运转，但是Yb:GYSO锁模激光器中存在的调Q锁模问题还有待进一步的理论分析和实验研究。最后，我们测试了国产Yb:YAG、Nd:YAG陶瓷的激光输出特性，实验结果表明国产激光陶瓷的制备工艺已获得了重大突破，国产激光陶瓷在未来将有良好的应用前景。主要的研究成果如下所示： 1. 采用波长 978nm的LD作为泵浦源，对5at.% Yb:LSO晶体的激光特性进行了实验研究，当激光输出波长为 1082nm 时，获得了3.24W的连续输出，对应的斜效率为55%。对于中心波长为1061nm的激光运转，得到了 3.1W 的最佳输出，光-光转换效率 55.4%，对应的斜效率为 64.7%。在波长调谐的实验中，获得了调谐带宽为67nm 的宽调谐激光输出，该带宽可以支持小于100fs的激光运转。 2. 基于SESAM被动锁模理论，我们研制了SESAM被动锁模的Nd:YVO4激光器。激光器获得了1.26W﹑15.7ps的连续锁模脉冲输出。实验中的稳定锁模阈值与理论阈值相符合，为下一步进行Yb:GYSO被动锁模实验提供了经验指导； 3. 基于Yb:GYSO增益介质的激光器运转在1081.5nm波段时，获得了2.44W的连续输出，对应的斜效率为57%，在调谐实验中获得了59nm的调谐带宽。Yb:GYSO的高效率及宽而平坦的调谐曲线说明Yb:GYSO晶体非常适用于锁模激光运转。在SESAM被动锁模Yb:GYSO的实验中获得了426mW﹑168MHz的稳定连续锁模脉冲输出，但Yb:GYSO锁模激光器中的调Q锁模问题还有待进一步分析和解决； 4. 研究了二极管泵浦的国产陶瓷激光器的输出特性。采用Nd:YAG陶瓷的激光器，获得了0.85W的输出功率，对应的斜效率为20.3%。而基于Yb:YAG陶瓷的激光器，获得了1.63W的输出功率，对应的斜效率为23.2%。 |
| 英文摘要 | Increasing attention has been focused on Yb3+-based laser systems since the rapid development of high power and high brightness laser diodes emitting at 900-980nm. Compared to Nd3+-doped materials, Yb3+-doped ones have only two electronic multiplets, which give rise to a simple electronic-level scheme, and contribute to a low intrinsic quantum defect, a weak thermal load, an absence of luminescence quenching, and an enhanced laser action. Also, the longer radioactive lifetimes of the upper laser manifolds of Yb3+-doped materials, i.e. increased energy-storage property, are favorable to enhancing the economic utilization of the diode pumps and hence the development of high-energy diode pumped sources. More important, because of stronger electron–phonon interaction, the broader absorption and emission spectra of Yb3+-doped materials allow diode pumping with relaxed temperature regulation constraints, wide tunability, and the production of ultrashort pulses. Therefore,Yb3+-doped crystals have been recognized in recent years as very interesting active media for diode pumped ultrafast laser oscillators and amplifiers. In this dissertation, we focused on the theoretical and experimental research on two novel Yb-doped lasers. Firstly, the laser performances of Yb:LSO crystals was experimentally investigated, high conversion efficiencies and broad tunable wavelength range have been achieved; Secondly, experiments on passively mode-locked Nd:YVO4 with SESAM have been carried on, the results of the experiments coincided with the theory threshold of stable mode-locking; Thirdly, the LD pumped Yb:GYSO passive mode-locked laser has been achieved. Favorable laser performances such as high conversion efficiency and broad wavelength tuning have suggested that Yb:GYSO are very suitable to be used for a mode locked laser operation, but the phenomenon of Q-switched mode-lock was still a problem in our experiments; Finally, two domestic ceramics lasers, namely Yb:YAG and Nd:YAG ceramics lasers was developed, experiment’s results showed that the domestic laser ceramic will have a favorable foreground in future. The main results are summarized as follows: 1. Using a LD emitting at 978nm, we investigated the laser performance of 5at.%Yb:LSO crystal. Laser operation at 1082nm was achieved for the first time as we know, the maximum output power was 3.24W and its slope efficiency reached 55%. Also, we experimentally investigated its tunable ability, and broad tunable wavelength ranges of 1017nm to1084nm were obtained. Its broad bandwidth could support mode locked operation with pulse duration of less than 100fs. Therefore, Yb:LSO is a potential laser medium for developing all-solid-state ultrafast laser. 2. Based on the principle of passively mode locking by SESAM, we have developed the SESAM passively mode-locked Nd:YVO4 laser. 1.26W、15.7ps mode-lock pulses was achieved and that the experimental threshold of stable mode-lock was coincident with the theory threshold. 3. 2.44W continuous output power and 59nm wavelength tunable range was achieved for Yb:GYSO laser. High efficiency and broad wavelength tuning suggested that Yb:GYSO are also very suitable to be used for a mode locked laser operation. In mode-locked Yb:GYSO laser, 426mW、168MHz stable mode-lock pulses was achieved. But Q-switched mode-locking is still a problem in mode-locked Yb:GYSO laser. 4. For Yb:YAG ceramic laser, 1.63W output power was achieved, corresponding to a slope efficiency of 23.2%. For Nd:YAG ceramic laser, 0.85W output power was achieved ,corresponding to a slope efficiency of 20.3%. These results showed that domestic laser ceramic had made great progress on laser performance. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16523]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 许毅. 掺Yb3+新型晶体激光特性的研究[D]. 中国科学院上海光学精密机械研究所. 2007. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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