种子注入的全固态单纵模激光器研究
文献类型：学位论文
| 作者 | 周军 |
| 学位类别 | 博士 |
| 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 | 陈卫标 |
| 关键词 | 全固态激光器 单纵模 种子注入 谐振探测 频率稳定 |
| 其他题名 | Study of injection-seeded single frequency all solid-state laser |
| 中文摘要 | 直接探测多普勒测风激光雷达在全球范围内正得到越来越广泛的应用，该雷达系统对激光发射源有很高的要求，不仅要求激光器能在一定功率水准上输出单纵模调Q脉冲，还要求单纵模激光器有很好的频率稳定性。本论文针对多普勒激光雷达的应用，对种子注入的单纵模调Q激光器进行了一系列的研究，主要包括原理性实验、实用机型研制、种子注入激光器的频率稳定性三个方面的内容。 在原理性实验阶段，首先设计了凸凹腔型基横模输出的谐振腔，利用该谐振腔得到了近30mJ@100Hz基模输出的Nd:YAG激光器，激光束两个方向的光束质量均小于1.5；然后对该激光器进行种子注入实验，利用建立时间最小化技术（build-up-time minimizing）和谐振探测技术（ramp-fire）均实现了稳定的单纵模调Q激光输出，并对谐振探测技术的两种改进方案，ramp-hold-fire技术和delay-ramp-fire技术进行了初步的实验，对其注入性能进行了比较。 在原理性实验的基础上，研制了实用化的355nm的全固态单纵模激光器，以作为直接探测多普勒测风激光雷达的发射光源。该器件的振荡级采用基于谐振探测种子注入技术的Nd:YAG激光器，在1064nm波长实现了大于25mJ@100Hz的单纵模基频输出，经过一级单程放大得到了近100mJ@100Hz的基频光，采用II类匹配的KTP晶体和I类匹配的BBO晶体进行三次谐波变换，实现了大于20mJ@100Hz的355nm激光输出，在355nm波长处的光谱线宽小于180MHz。激光器各项技术参数达到了预先设定的指标，能满足直接探测多普勒测风雷达对激光发射源的要求，目前正参与激光雷达系统的测风实验。 对种子注入Nd:YAG激光器的频率稳定性进行了细致的研究，建立了单纵模调Q激光器的频率稳定性测量装置，该装置采集种子光与调Q脉冲光的混频信号，利用LabVIEW软件编写程序对混频信号进行频谱分析，以拍频率的稳定性衡量单纵模调Q脉冲激光的频率稳定性。利用该装置对各种注入控制方法实现的单纵模激光输出进行了频率稳定性的测量和比较，分析了谐振探测技术中引起较大频率抖动的原因，通过对现有的注入控制系统的优化，实现了较好的频率稳定性，使单纵模Nd:YAG调Q激光器的频率抖动范围小于5MHz，rms小于0.5MHz。最后提出了新的改进方案，理论分析表明该方案优于现有的控制方案，能在降低控制系统难度的同时进一步提高种子注入激光器的频率稳定性。 本文研究的激光器件解决了高功率全固态激光器的窄线宽输出问题，不仅可以应用于多普勒激光雷达，也可以应用于其它光谱测量的激光雷达、以及激光通信等领域。 |
| 英文摘要 | The direct-detection Doppler wind lidar is very important for global wind profiles measurement. The lidar imposes special requirements on the single frequency laser transmitter. Not only high power but also high frequency stability was important. Based on the application of the wind lidar, the injection seeded single-longitudinal-mode laser is studied in detail. Three parts including fundamental experiments, practical laser transmitter and frequency stability are presented. A fundamental mode Nd:YAG laser with convex-concave resonator is designed firstly. The output energy of 30 mJ is obtained at the puls repetition rate of 100Hz. The M2 values of horizontal and vertical axes are less than 1.5. The experiment of injection seeding is implemented. Stable single-longitudinal-mode Nd:YAG laser is achieved by build-up-time minimizing technique and ramp-fire technique respectively. Two improved solutions based on ramp-fire technique, ramp-hold-fire and delay-ramp-fire, are implemented experimentally. The stability of injection seeding is compared. The second part describes the development of a 355nm all-solide-state single frequency laser. This laser is developed for a direct-detection Doppler wind lidar. 1064nm single-longitudinal-mode Q-swithed pulses with energy of 25mJ at 100Hz are achieved in an injection seeded Nd:YAG oscillator. The energy of the laser pulses are amplified to 100mJ by following another pump head. The single frequency 1064 nm output of the oscillator/amplifier is converted to its harmonic at 355 nm by using a Type II KTP crystal for the second harmonic generation and a Type I BBO crystal for the third harmonic generation. The pulse energy of more than 20mJ and the frequency linewidth of less than 180MHz are demonstrated at 355nm. The major technical parameters of the laser reach the expected standard. A Doppler wind lidar measurement experiment is on-going by using this laser transmitter. The frequency stability of an injection seeded Nd:YAG laser is studied in detail. A device for measuring the frequency stability of single frequency Q-switched pulses is developed firstly. The frequency-mixing signal is acquired by a DAQ with a sampling rate of 2GHz. The spectral analysis of the signal was carried out by a LabVIEW program. The frequency stability of the single frequency Q-swithed pulses is characterized by the stability of the beat frequency. The frequency stabilities of several injection seeding solutions are measured and compared. The reasons of the large frequency jitter presented in ramp-fire technique are analyzed. A frequency range of less than 5MHz is achieved by improving the injection seeding control system. The frequency stability(rms) is less than 0.5MHz. At the end of this part a new improved solution is introduced. Theoretical analysis indicates that this solution is better than present control scheme. Frequency stability of the injection seeded Nd:YAG laser will be further improved by this solution while the control system is relatively simple to perform. The studies in this dissertation solve the problem of narrow linewidth output in high power laser. The laser can be applied to not only Doppler wind lidar but also other lidar for spectral measurement and laser communication. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15309]  |
| 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 | 周军. 种子注入的全固态单纵模激光器研究[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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