| 题名 | 超短脉冲光子晶体光纤放大与其频率转换特性研究 |
| 作者 | 王子薇 |
| 学位类别 | 博士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 周军 |
| 关键词 | 光纤激光器 主振荡-放大 超短脉冲 光子晶体光纤 倍频 |
| 其他题名 | Study on ultra-short-pulse photonic crystal fiber amplification and frequency conversion properties |
| 中文摘要 | 超短脉冲激光器在激光显示、材料加工、医疗美容等领域有着非常广阔的应用前景。近年来，随着大功率半导体包层泵浦技术的进步和新型光子晶体光纤（PCF）的不断出现，使得高功率掺镱超短脉冲光纤激光器和放大器的性能大幅提升，在效率、体积、成本、散热、可靠性和光束质量上，相对于传统的固体激光器都具有非常明显的优势。将光纤激光技术与非线性频率转换技术相结合，通过倍频产生高光束质量、高功率的蓝绿激光，已成为固体激光技术领域的一个研究热点。本论文围绕实现高峰值功率、高平均功率、高光束质量、高倍频效率的超短脉冲光纤激光输出这一目标，选取基于锁模超短脉冲种子源和超大模场PCF的主振荡-功率放大（MOPA）技术方案，开展了超短脉冲PCF放大的理论和关键技术、高平均功率和高峰值功率皮秒PCF放大特性，以及皮秒脉冲倍频特性等方面的研究工作。 第一章介绍了掺镱光纤激光器以及PCF的基本特性，分析了光纤激光器实现超短脉冲激光输出的几种方案，重点介绍了基于主振荡-放大技术的超短脉冲光纤激光及其高效倍频技术，在此基础上总结了高功率超短脉冲光纤激光器的发展瓶颈以及未来发展趋势。 第二章分析和探讨了高峰值功率脉冲光子晶体光纤激光放大中的理论和关键技术。首先，基于脉冲掺镱光纤放大器的理论模型，研究了掺镱光纤的储能特性，考虑了抑制放大的自发辐射，模拟了PCF放大的输出特性。其次，研究了高峰值功率脉冲光纤激光器与放大器中的各种非线性效应对脉冲光纤放大的影响，并给出了相应的阈值判定方式，并着重分析了自相位调制与群速度色散效应对超短脉冲放大光谱和脉冲的影响。随后，介绍了光纤的材料损伤与自聚焦效应对光纤放大的影响，开展了光子晶体光纤的处理工艺的研究和探索，初步掌握了光子晶体光纤切割、熔接、端面处理等技术。 第三章分析了基于MOPA结构的超光纤放大系统设计的基本准则，并针对PCF光纤放大系统进行了方案设计和实验研究。基于自研超大模场直径空气包层型PCF和SESAM锁模光纤激光器，实现了平均功率255W的1030nm激光输出。该PCF纤芯/内包层直径105/375μm，外包层直径670μm，没有涂覆层。纤芯/内包层NA=0.05/0.46，在976nm处的吸收效率达到了24dB/m。在脉冲宽度21ps、重复频率10.26MHz时，输出脉冲对应的峰值功率达到了1.18MW，单脉冲能量达到了25μJ，斜率效率约为77%。在最大功率下，信噪比达到了35dB，较好地抑制了光纤中的ASE和非线性效应。此外，我们还基于自研的AS-PBGF进行了放大实验。采用纤芯/内包层直径约为60/293μm，NA为0.03/0.46，在970nm处的吸收为4 dB/m。在同样的放大条件下，获得了平均功率80W的激光输出。我们首次实现了国产PCF百瓦以上皮秒激光输出，显示了PCF在超短脉冲领域的高平均功率与高峰值功率潜力。 第四章针对窄线宽、高峰值功率、高光束质量的皮秒PCF放大系统展开了研究。基于脉冲宽度、重复频率可调的锁模激光器作为种子源，Rod-PCF作为主放级增益光纤，获得了峰值功率高达2.94MW的近衍射极限激光输出。分析了不同脉冲宽度、重复频率、入射条件下对放大输出的影响；以及脉冲宽度在200ps下对Rod-PCF的损伤条件。随后，基于Rod-PCF，通过两级光纤保偏放大，实现了峰值功率3.4MW，偏振消光比达15dB的脉冲激光输出，为后续绿光倍频系统提供了性能优越的基频光源。 第五章开展了皮秒光纤激光器的倍频技术研究。介绍了超短脉冲光纤激光的倍频理论、倍频晶体和相位匹配条件，模拟了LBO晶体倍频1030nm超短激光的方案。基于温度匹配的LBO晶体，获得了峰值大于1MW的515nm绿光输出，其最高倍频效率大于56%。 |
| 英文摘要 | The technology and applications of miniature, high-efficiency ultra-short-pulse lasers on laser display, material processing and medical treatments have broad prospective. In recent years, output properties from ultra-short-pulse Yb fiber lasers and amplifiers raised up dramatically via the use of semiconductor cladding pumping technology and photonic crystal fibers (PCF). Comparing with traditional solid lasers, fiber lasers has outstanding superiority in efficiency, volume, expense and so on. Combing advantages of fibers laser with nonlinear frequency conversion technology can produce blue-green lasers with high quality and high power, which have become one of the research focuses in solid laser research fields at present. In this dissertation, to study ultra-short-pulse blue-green laser with high-peak-power, high-average-power, high-beam-quality and high conversion efficiency, this dissertation focuses on the theory and key technique of short-pulse PCF amplification, high-peak-power and high-peak-power properties and frequency conversion properties. The main contents are as follows: In Chapter I, Yb-doped fiber laser properties are introduced; then several methods of obtaining ultra-short-pulse by fiber lasers are listed, and it is emphasis on latest progresses and development trends of fiber master-oscillator power amplification (MOPA) system and frequency conversion technique. Moreover, development bottleneck and trend of high-power pulse fiber laser are summarized. In Chapter Ⅱ, theory and key technique of ultra-short-pulse PCF amplification are discussed and analyzed. Based on the virtue of laser power transmission equations and the physical model of pulsed Yb-doped fiber amplifier, the methods to suppress amplified spontaneous emission (ASE) and increase extracted energy are considered; the numerical simulation of our system is established. Furthermore, the limitations of nonlinear effects in high-peak-power fiber lasers and amplifiers are introduced and analyzed; the influence of self-phase modulation (SPM) and group velocity disperasion (GVD) to spectrum and pulse are clearly analyzed. Moreover, the damage threshold of fused silica and self-focus effect are considered. Cutting and splicing of photonic crystal fibers are experimentally studied; end facet treatment of fibers is also introduced. In Chapter Ⅲ, the amplification properties of high-average-power and high-efficiency picosecond pulses in a self-made very-large-mode-area air-clad Yb-doped PCF are studied. The PCF with core diameter of 105μm and core numerical aperture (NA) of 0.05 is prepared by sol-gel method combined with powder sintering technique. The fiber amplification system produces the highest average power of 255W at 10MHz repetition rate with 21ps pulse duration corresponding to peak power of 1.2MW, pulse energy of 25μJ and slope efficiency of 77%. Moreover, performance of self-made all-solid photonic bandgap fiber is also evaluated in high power laser amplifier configurations. With core/inner cladding diameter of 60/293 μm, core/inner cladding NA of 0.03/0.46 and pump absorption of 4 dB/m@976nm, maximum power of 80W is obtained with the same amplifier configuration of air-clad fibers. This is the first picosecond fiber lasers reached hundreds of watts from domestic PCFs，which exemplifies the high-average-power and high-peak-power potential of this specific-designed fiber. In Chapter Ⅳ, the picosecond fiber laser with narrow linewidth, high-peak-power and high-beam-quality is demonstrated. Based on 1030nm mode-locked tunable fiber laser，multi-stages of all-fiber preamplifiers and ultra-large-mode-area rod-type PCF, near-diffraction-limited pulses with maximum peak power of 2.94MW and PER of 15dB is reported. The output properties of peak power, spectrum and pulse width are compared with different repetition rates, pulse widths and Incident conditions. Moreover, polarization-mataining amplification of picosecond pulses is archived; near-diffraction-limited pulses with maximum peak power of 3.4MW and PER of 15dB is reported. It is excellent fundamental source for frequency conversion system. In Chapter Ⅴ, second harmonic generation technique of picosecond lasers is explored. The theory of frequency doubling, crytals and phase matching is introduced. Based on the narrow linewidth, high-peak-power and high-beam-quality fiber laser, Type Ⅰ phase matching to LBO is achieved, and the maximum output peak power at 515nm is 1MW with conversion efficiency above 56%. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15959]  |
| 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 | 王子薇. 超短脉冲光子晶体光纤放大与其频率转换特性研究[D]. 中国科学院上海光学精密机械研究所. 2016. |
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