| 题名 | 高平均功率脉冲光纤放大器与光纤激光倍频技术研究 |
| 作者 | 刘侠 |
| 学位类别 | 博士 |
| 答辩日期 | 2010 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 楼祺洪 |
| 关键词 | 脉冲光纤放大器，脉冲波形畸变，大模场面积双包层光纤，窄线宽，线偏振，倍频 |
| 其他题名 | Study on high-average-power pulsed fiber amplifier and frequency doubling of fiber laser |
| 中文摘要 | 掺Yb3+的高功率双包层光纤激光器的研究和应用是目前国内外激光研究领域的热点之一。同传统的固体激光器相比，光纤激光器无论在效率、体积以及光束质量等方面，均占有明显的优势。其中，脉冲的光纤激光器的研究对目前和潜在的应用尤为重要，如在医疗、科研、军事、材料加工等领域；另一方面，窄线宽线偏振光纤激光源的开发以及通过倍频技术获得不同波长（尤其是可见光波段）的高功率光纤激光同样具有极好的研究价值和应用前景。本文首先从理论和实验两方面对高平均功率的脉冲光纤放大器进行了研究；其次，分别实验研究了脉冲和连续工作方式的窄线宽线偏振光纤激光器；最后基于所获得的窄线宽线偏振光纤激光对光纤激光倍频技术进行了一定的探索。 第一章列出了采用种子源主振荡－放大(MOPA)、调Q和锁模三种技术实现脉冲光纤激光输出的手段，重点介绍了基于MOPA系统获得高峰值功率、高脉冲能量的激光脉冲的新进展。此外，分析了窄线宽线偏振光纤激光的实现方法，综述了国内外分别采用外腔单通倍频、内腔倍频与外腔谐振倍频这三种方式获得倍频光纤激光输出的新进展。 第二章根据激光功率传输方程和掺Yb3+双包层光纤放大器的物理模型，采用有限差分法对掺Yb3+光纤放大器的高功率放大特性进行了计算模拟，并对放大过程中的脉冲波形畸变及其控制进行了理论和实验两方面的研究。 第三章首先分析了高平均功率脉冲双包层光纤放大器的关键技术。随后，采用国产大模场掺Yb3+双包层光纤，基于空间耦合的MOPA放大方式，成功实现了平均功率高达156W的1064nm脉冲激光输出，输出的脉冲重复频率在50kHz-150kHz之间连续可调，脉冲宽度在20ns左右。最后，在上述研究的基础上，进一步采用全光纤MOPA放大方式获得了平均功率为101W的脉冲激光输出，输出脉冲重复频率50kHz，脉冲宽度13ns左右。 第四章首先对倍频理论进行了简单分析。然后，利用双包层保偏光纤缠绕、端面磨布儒斯特角等方法控制光纤激光的偏振和模式特性，同时通过在双包层有源光纤上焊接光纤光栅控制输出线宽，获得了输出功率高于10W的窄线宽(FWHM <0.2nm)、线偏振(PER>21dB)的1085nm连续光纤激光源，并通过非临界相位匹配的LBO晶体进行了光纤激光内腔倍频实验的探索，获得的最大谐波输出功率为250mW。最后，采用全光纤调Q方式的脉冲种子源获得了窄线宽脉冲激光MOPA系统，实现了最高平均功率为14W的窄线宽（光谱半高全宽FWHM<0.12nm）、线偏振（偏振消光比PER≈13dB）的1080nm脉冲光纤激光输出。上述实验所获得的窄线宽脉冲光纤激光，经非临界相位匹配的KTP晶体以外腔单通倍频的方式获得了3.5W的倍频绿光输出，相应的光-光转换效率达27.3%。 |
| 英文摘要 | The technique and applications of high power Yb3+-doped double-cladding fiber laser is one of the research focuses in international research fields at present. Comparing with traditional solid lasers, fiber laser has distinguished superiority in efficiency, volume, beam quality and so on. Especially, the pulsed fiber laser is very important for the present and potential application including medical treatments, scientific researches, military affairs, material processing and so on. On the other hand, it also possesses excellent research value and potential application for the developing the fiber laser with narrow linewidth and linear polarization and generating high power fiber lasers with various wavelength (especially for the visible region) based on frequency doubling. In this dissertation, theoretical and experimental study on high-average-power pulsed fiber amplifier is presented firstly. Then the pulsed or continuous-wave(CW) fiber laser with narrow linewidth and linear polarization was experimentally studied. Finally the technique of frequency doubling of fiber laser with narrow linewidth and linear polarization was explored. In the first chapter, three scheme of pulsed fiber laser including the master-oscillator power amplifier (MOPA), Q-switched and mode-locked techniques are demonstrated, and it was emphasis on the latest progresses and development trends of pulsed fiber MOPA systme with higher peak power and higher pulse energy. Besides, the method of generating fiber laser with narrow linewidth and linear polarization was analyzed, and the latest progresses and development trends of frequency doubled fiber lasers using single-pass frequency doubling, intracavity frequency doubling or external-cavity frequency doubling was also reviewed. In the second chapter, the high-power amplification characteristics are analyzed by virtue of laser power transmission equations and the physical model of Yb3+-doped fiber amplifier. Besides, the pulse waveform distortion of amplified pulse signal and the active control of it were investigated theoretically and experimentally. In the third chapter, the key techniques of high average power pulsed double-cladding fiber amplifier are analyzed firstly. Secondly, a MOPA system using free space coupling technique was constructed by China-made large-mode-area(LMA) fiber. The system can generates up to 156-W average power of amplified radiation at a wavelength of 1064nm with adjustable repetition frequency of 50~150kHz and pulse duration about 20ns. Finally, on the fundation of the above work, a 101-W average power pulsed laser was obtained from an all-fiber MOPA system and its repetition frequency and pulse duration were 50kHz and 13ns, respectively. In the fourth charter, the principle of the frequency doubling is briefly analyzed. Then a 10W CW fiber laser with narrow linewidth (<0.2nm FWHM) and linear polarization (PER>21dB) was obtained by using the Brewster’s angle-polished fiber end and coiling the polarization-maintaining(PM) fiber to control the polarization and mode characteristics of the fiber laser together with including a narrow-linewidth fiber grating into the laser cavity to control the linewidth of the output. Based on the above method the intracavity frequency doubling of fiber laser was studied using a non-critical phase matching LBO crystal and a maximum 250mW second harmonic wave was generated. Finally, a MOPA system which can provide narrow linewidth pulsed laser was constructed by an all fiber Q-switched laser used as seed laser. The system can generates up to maximum 14W average power of amplified radiation with narrow linewidth (<0.2nm FWHM) and linear polarization(polarization extinction ratio PER≈13dB) at 1080nm. Based on the pulsed amplified radiation with narrow linewidth, 3.5W green laser was obtained by single-pass frequency doubling using non-critical phase matching KTP crystal and its optical-optical efficiency was 27.3%. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15628]  |
| 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 | 刘侠. 高平均功率脉冲光纤放大器与光纤激光倍频技术研究[D]. 中国科学院上海光学精密机械研究所. 2010. |
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