基于全固态皮秒激光器的腔倒空技术研究
文献类型：学位论文
| 作者 | 付翔 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013 |
| 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 | 全固态激光器 锁模激光器 腔倒空技术 Herriott型多通腔 |
| 其他题名 | Studies on cavity dumping technique based on picosecond DPSSL |
| 中文摘要 | 随着科技日新月异地发展，激光在人民生活、国防安全和科学研究中都发挥着无法替代的重要作用。从上世纪80年代开始，半导体激光技术迅猛发展。许多不同种类、性能优良的半导体激光器的相继面世，极大促进了以此为泵浦的全固态激光器(DPSSL)的发展。全固态激光器集半导体激光器和固体激光器的优势于一身，具有长寿命、高效率、光束质量好、高可靠性和多样的运转模式等优点，已经成为激光器发展中最具前景的方向之一。如今，高功率、高单脉冲能量的全固态激光器被广泛使用在工业、医疗和科研等许多领域，涵盖微加工、激光打标、激光手术、组织操纵、非线性频率转换和超快激光光谱等众多方面。为了能够获得高能量的激光输出，人们提出了腔倒空技术。它能够在不增加激光器的复杂度，仅通过在腔内插入倒空模块的情况下实现高能量的脉冲输出。正因为它结构简单且效果显著，腔倒空技术在超快激光器设计中，特别是皮秒、飞秒激光器的设计中，经常被使用。 本论文以研究Nd:YVO4的全固态振荡器为基础，尝试使用腔倒空技术和MPC结构来提高全固态激光器的输出功率、紧凑全固态激光装置的结构。所做工作主要包含以下几个方面： 1. 设计并搭建了最高输出功率为12.1 W、重复率为64 MHz、脉宽为16 ps的高功率Nd:YVO4全固态皮秒激光振荡器。采用带内泵浦方式，使用中心波长为880 nm的半导体激光器作为泵浦源，有效地减小Nd:YVO4晶体的热效应。以半导体可饱和吸收镜（SESAM）作为锁模器件进行锁模。在泵浦功率为26.4 W的条件下，获得了12.1 W的锁模脉冲输出，对应45.8%的光-光转换效率和61.2%的斜效率。输出激光的光束质量良好，在两个正交方向上的M2因子均不大于1.09。相比同类型的皮秒振荡器，该激光器具有较高的输出功率。 2. 设计了一个单程附加光程为4.5 m、保Q效果良好的两镜腔结构MPC。在了解MPC的原理之后，利用Matlab编写了MPC的模拟程序。本程序建立了两种对光线进行追迹的算法，一种是将文章中介绍的MPC中光线离轴传输路径的理论进行代码化，另一种是对光线利用基本几何光学定律逐步追迹。通过比较两种算法得到的MPC腔镜上光斑分布模拟图，了解了两种算法的差异并指出离轴传输理论算法上的缺陷。通过对Herriott型多通腔（MPC）结构进行理论研究和程序设计后搭建了一个MPC，并将该MPC应用到之前实验所设计的Nd:YVO4晶体全固态皮秒激光器中，使该激光器的输出脉冲重复率由64 MHz降到22 MHz。虽然使用MPC后，激光器的最大输出功率从12.1 W降至10.5 W，但是单脉冲能量却从0.19 μJ提高到了0.48 μJ。 3. 设计并实现了含有MPC结构的腔倒空式振荡器，获得脉冲宽度为14 ps、单脉冲能量为3 μJ且光斑质量良好的倒空脉冲输出。对上述第2点中含有MPC的Nd:YVO4全固态皮秒振荡器使用腔倒空技术。通过在该腔中插入偏振片和使用RTP晶体的普克尔斯盒（PC）形成的腔倒空结构，搭建出利用MPC的腔倒空式振荡器。该振荡器利用22 MHz腔内锁模脉冲信号得到100 KHz的倒空同步信号来控制PC，实现100 KHz的倒空输出。更高单脉冲能量的输出有望通过对腔型地进一步优化、泵浦和腔内模式更好地匹配以及使用损耗更低的MPC腔来达到。 |
| 英文摘要 | With the rapid development of science and technology, laser has played an indispensably important role in daily life of human beings, national defense and security and scientific research. Since 1980’s, there is a giant leap in techniques about semiconductor lasers. The introducing of variety of well-performed semiconductor lasers boosted the development of diode pumped solid-state lasers (DPSSLs) which use semiconductor lasers as pump sources. By combining the benefits of semiconductor lasers and solid-state lasers, DPSSLs have long service life, high efficiency and reliability, good beam-quality, and various operating modes, thus already being one of the most promising advancing directions of lasers. High power and high pulse energy DPSSLs have been widely used in industry, medicine and science research etc. with numerous applications such as micromachining, laser marking, laser surgery, tissue manipulation, nonlinear frequency conversion and ultrafast spectroscopy. To increase the pulse energy of DPSSLs, cavity dumping technique is applied for the reason that it can realize high energy output pulse by inserting dumping module while keeps the structure compact. This technique has been frequently used in ultrafast laser design, especially in picosecond and femtosecond laser design, for its simplicity. In this dissertation, we made a trial in improving output power and compacting the structure of DPSSLs through applying cavity dumping technique and MPC structure, based on the studies of Nd:YVO4 DPSSLs. The main results are summarized as follows: 1. A high power picosecond Nd:YVO4 DPSSL with 12.1 W maximum output power at repetition rate of 64 MHz and duration of 16 ps was demonstrated. Using semiconductor laser whose central wave length was 880 nm as pump at intra-band pumping style to reduce thermal effects on Nd:YVO4 crystals. Mode locking was accomplished by using a semiconductor saturable absorbers mirror (SESAM) as mode locking component. The maximum output power was 12.1 W at the pump power of 26.4 W, corresponding to optical-to-optical conversion efficiency up to 45.8% and slope efficiency of 61.2%. The M2 factors of output laser beam were no more than 1.09 in both orthogonal axes implied good beam quality. Compared with its counterparts, this laser had a relatively high output power. 2. A well Q-preserved two-mirror MPC with 4.5 m additional optical length was designed. After investigating the theory of MPC, we used Matlab to simulate MPC. We had two ways to trace the laser beam propagation in MPC: One is using theory of off-axis path transmission in MPC; the other is tracing the beam step by step by applying basic laws of geometrical optics. Through comparing the simulating patterns of spots on mirrors, we found the difference between two algorithms and the defect in off-axis path transmission theory. Applying this accomplished MPC to Nd:YVO4 picosecond DPSSL referred above, we found the repetition rate of DPSSL output pulse was lowered to 22 MHz from 64 MHz. Although the average output power decreased from 12.1 W to 10.5 W corresponding to a 13% loss, the pulse energy was more than doubled which rose from 0.19 μJ to 0.48 μJ. 3. A cavity-dumped DPSSL with MPC was demonstrated. It had pulse duration of 14 ps and 3 μJ single pulse energy with gaussian energy distribution in cross profile of laser beam. Cavity dumping technique was used in above Nd:YVO4 DPSSL with MPC. By inserting RTP Pockels Cell (PC) and Thin Film Polarizer (TFP) in DPSSL with MPC, we got this cavity-dumped DPSSL with MPC. In this laser, a 100 KHz synchronizing cavity dumping signal was produced to control PC by 22 MHz signal from mode-locked pulses in cavity to realize 100 KHz dumping output. The higher pulse energy may be achieved by optimizing the cavity design, better matching between pump and mode in cavity and lowering the loss of MPC. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16774]  |
| 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 | 付翔. 基于全固态皮秒激光器的腔倒空技术研究[D]. 中国科学院上海光学精密机械研究所. 2013. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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