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题名	三能级脉冲光纤激光技术研究
作者	何晶
学位类别	博士
答辩日期	2014
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	掺镱光纤 三能级系统 大模场面积光子晶体光纤 声光调Q 脉冲激光器
其他题名	Study on three-level pulsed fiber laser technique
中文摘要	脉冲光纤激光器是目前光纤激光领域非常活跃的研究方向之一，随着激光器性能的不断提升，应用领域也不断拓展。波长在980 nm附近的三能级掺镱光纤激光及其通过非线性频率转换技术得到的相干激光在硅基探测、水下通信、材料加工等领域有着极其重要的应用，具有很大的研究价值。基于此类应用需求，本论文以获得高峰值功率、高脉冲能量、线偏振的纳秒量级调Q三能级脉冲光纤激光为目标，对三能级光纤激光器以及其调Q脉冲特性进行了深入的研究。 第一章综述了三能级光纤激光器的基本概况。总结了掺镱石英双包层光纤和光子晶体光纤的特性。分别从连续、调Q脉冲、锁模脉冲几个方面，对国内外三能级光纤激光器的发展历程和实现技术进行了详细的综述，并给出了国内外研究机构的一些典型研究成果。 第二章以实现有效的三能级连续激光输出为目标，对三能级和准四能级模式的激光振荡进行了理论和实验的研究。从理论上分析了掺Yb光纤中两种模式产生的背景和条件，明确了产生有效三能级运转的必要条件。从实验上，通过采用超大模场面积的新型光子晶体光纤以及强泵浦条件再加入腔内滤波控制，分别获得了7 W的978 nm以及13 W的1034 nm激光输出。通过两种模式下激光器输出参数的对比，进一步地分析了掺Yb光纤中准四能级跃迁和三能级跃迁的增益竞争优势问题。 第三章研究了调Q光纤激光器中的脉冲输出特性。研究了一种准四能级的单端光纤耦合全光纤化掺Yb双包层调Q脉冲激光器，在50 kHz重频下激光器得到了2.6 W平均功率，56 ns脉冲、中心波长0.06 nm光谱宽度的高效率调Q脉冲输出。基于该激光器的结构，对调Q光纤激光器中普遍存在的调Q脉冲参数变化、降频等问题开展了一系列详细的分析和讨论。研究发现调制信号的频率、占空比等因素都会造成激光器输出脉冲状态的变化。进一步根据输出脉冲的状态划分激光器工作区域，总结和归纳了不同分区下脉冲的工作特性，为各种调Q光纤激光器输出参数的优化提供了指导意义。 第四章基于超大模场光子晶体光纤实现了一种978 nm的线偏振、高峰值功率、高脉冲能量、短脉冲的调Q光纤激光器，在重复频率10~200 kHz下可以得到低于50 ns脉宽的稳定脉冲序列，在10 kHz下获得了峰值功率130 kW、脉冲能量120 μJ，脉冲宽度9 ns的窄脉冲输出。同时，利用调制信号占空比的可控性，实现了少有的重复频率可高达10 MHz，脉冲宽度十几纳秒的调Q脉冲。然后基于该振荡器探索了978 nm的线偏振调Q脉冲光纤激光的倍频特性，对BBO晶体实现I类角度相位匹配，获得了最大280 mW的489 nm蓝绿激光，并分析了提高倍频效率的优化方案。
英文摘要	Pulse fiber laser is one of the research hotspots in the field of fiber laser at present. With the continuous improvement of laser performance, the applications of pulsed fiber sources are expanding rapidly. The three-level Yb-doped fiber laser around 980 nm and its frequency doubling light, which play an important part in the application of silicon-based detection, underwater communication, materials processing and other fields, are of great research value. Based on these application requirements, to obtain high peak power, high pulse energy, linearly polarized, ns-class Q-switched three-level fiber laser, the study of three-level fiber laser sources and characteristic of Q-switched pulse is presented in this dissertation. In the first chapter, the general situation of three-level fiber laser is introduced. Properties of Yb-doped double cladding fiber and photonic crystal fiber are summarized. Domestic and overseas development and implementation of the three level fiber laser systems from three aspects of continuous wave, Q-switched pulse and mode-locked pulse techniques, are detailed reviewed. Some typical research results are presented. In the second chapter, to obtain effective three-level continuous laser output, laser oscillations in the three-level mode and quasi-four-level mode are demonstrated by theoretical and experimental study. In theory, background and conditions of the two modes in the Yb-doped fiber are analyzed and necessary conditions of effective three-level operation are also indicated. By adopting novel large-mode-area photonic crystal fiber, strong pumping condition and cavity filter control, laser outputs of 7 W at 978 nm and 13 W at 1034 nm are obtained experimentally. Gain competitive issues of quasi-four-level transition and three-level transition in Yb-doped fiber are further analyzed through the comparison of laser output parameters in two modes. In the third chapter, the output pulse characteristics of Q-switched fiber laser are studied. A single-ended fiber coupled actively acousto-optic Q-switched all-fiber laser is experimentally demonstrated. At the repetition rate of 50 kHz, laser system output high efficiency short pulses with average power of 2.6 W, pulse duration of 56 ns and laser wavelength is centered in 1080 nm with 0.06 nm line-width. Based on the structure of this laser, problems of the changes of Q-switched pulse parameters and repetition rate reduction are analyzed and discussed in detail. It is found that the variation of modulation signal frequency, duty ratio and other factors can result in changes of the laser output pulse parameters. The laser working region is divided into several parts according to the working state of the output pulses. The characteristics of output pulses in different partitions is generalized and summarized, which can provide significant guidance for the optimization of various kinds of Q-switched fiber laser output parameters. In the fourth chapter, based on the large-mode-area photonic crystal fiber, a linearly-polarized, high peak power, high pulse energy, short-pulse, Q-switching Yb-doped fiber laser at 978 nm is demonstrated. Less than 50 ns stable output pulses are achieved within repetition range of 10 kHz~200 kHz and short pulse of 9 ns pulse duration, 130 kW peak power, 120 μJ pulse per energy at 10 kHz can be reached. In the meantime, by controlling of the modulation signal duty cycle, rare reported Q-switched short pulses with pulse duration of a dozen ns, repetition rate up to MHz is obtained. by frequency conversion. Based on this fiber oscillator, frequency doubling of 978 nm fiber laser is explored. By implementing type I phase matching in BBO, blue light at 489 nm with maximum output power of 280 mW is generated. At last, the optimization scheme of improving frequency doubling efficiency at 978 nm is discussed.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15892]
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	何晶. 三能级脉冲光纤激光技术研究[D]. 中国科学院上海光学精密机械研究所. 2014.

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