| 题名 | 超短脉冲光纤激光技术研究 |
| 作者 | 王兆坤 |
| 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 被动锁模 低重复频率 等效可饱和吸收体 SESAM |
| 其他题名 | Research on ultrashort pulse fiber laser technology |
| 中文摘要 | 超短脉冲激光具有窄脉冲宽度、高峰值功率等优点，被广泛的应用到微机械加工、国防军事、生物医学诊断等多个领域。目前，获得超短脉冲的方法主要包括调Q技术以及锁模技术，其中，被动光纤锁模技术是实现小型化超短脉冲激光输出的有效技术手段。本文对基于等效可饱和吸收体以及SESAM的1μm波段的被动锁模光纤激光器进行了详细研究，并在此基础上利用增加长腔长以及利用声光调制器进行选单降频获得了低重复频率、高能量以及波长可调谐的超短脉冲输出。论文主要内容如下： 第一章首先介绍了超短脉冲的研究背景以及研究意义，然后详细介绍了基于SESAM、碳纳米管、石墨烯以及等效可饱和吸收体的被动锁模激光器的研究进展。最后介绍了脉冲的演变特性的发展。 第二章主要介绍了被动锁模光纤激光器的基本理论。由麦克斯韦方程组出发，最终推导出了能够同时体现着色散、非线性以及增益三种效应的描述锁模光纤激光器中脉冲传输的Ginzburg-Landau方程。 在第三章中研制了基于等效可饱和吸收体的1μm波段的被动锁模光纤激光器。主要研究了长腔条件时低重复频率锁模激光器的输出特性，观察到了矩形脉冲的输出。在NPR的长腔结构中引入负色散的啁啾光纤光栅作为限模元件，获得了基频221kHz，脉宽调谐范围从18.7ns-98.5ns。在此基础上，对产生的方波脉冲进行了放大，获得了输出功率大于130W 、偏振度大于18dB的输出。其次在长腔的NPR结构中，通过带通滤波器与Loyt的结合，实现了单波长可调谐、双波长的耗散孤子以及耗散孤子共振多种形式的输出，观察到了“阶梯状”矩形脉冲并分析了其形成原因。为了进一步获得低重复频率的窄脉宽的超短脉冲。本文基于NPR结构的锁模种子源，利用声光调制器进行了降频实验，获得了脉冲宽度为~21ps、重复频率在20KHz-~4MHz可调谐的输出的脉冲输出。 第四章主要研究了基于SESAM的1μm波段被动锁模光纤激光器，研制出了窄线宽（光谱3dB带宽<0.4nm）的超短脉冲光纤激光器样机。分别采用了啁啾光纤光栅、光环形镜、带通滤波器以及光纤光栅等四种不同的器件作为反射腔镜，搭建了基于SESAM的线型腔结构的被动。其中，在利用光栅光纤，获得了全保偏结构的中心波长为1030nm、脉冲宽度约为10.4ps的近转换极限的窄线宽的稳定锁模输出。同时，研究了波长可转换以及可调谐的窄线宽锁模实验，实现了锁模波长1022nm-1061nm的可调谐输出。 在第五章中探索研究了2μm波段的被动锁模掺铥光纤激光器。搭建了基于NPR效应以及以碳纳米管作为可饱和吸收体的被动锁模掺铥光纤激光器，在两种结构中都实现了锁模脉冲的输出。其中，在基于碳纳米管的锁模光纤激光器中观察到了双波长可调谐的锁模输出现象，并对其原因进行了分析。 |
| 英文摘要 | Due to its unique features like short pulse width, high peak power, ultra-short pulse sources have a wide range of applications in many fields of micro machining, material defense, biomedical diagnostics and so on. Currently the main method of obtaining ultra-short pulse includes Q-switch and mode-locking technique, wherein passive mode-locking fiber optic technology is the primary method for obtaining ultrashort pulses. In this paper, a detailed study on the passively mode-locked fiber lasers based on equivalent saturable absorber and SESAM is carried on. And furthermore, on this basis, the adapting methods of extended cavity length and acousto-optic modulator assist in obtaining a down-low repetition rate, high energy and wavelength tunable ultrashort pulse output. Several work is carried out as follow: In the first chapter, this thesis introduce the research background and significance of ultrashort pulses. And then we force on the advances in passively mode-locked laser based on SESAM, carbon nanotubes, graphene and equivalent of the saturable absorber. At last the evolution of the characteristics of the pulse is described. In the second chapter, we present the basic theory of passively mode-locked fiber laser. And by the Maxwell equations, we finally deduce the Ginzburg-Landau equation which simultaneously embodies the dispersion, nonlinear gain three effects and describes accurately o transmission of ultrashort pulses in fiber. In the third chapter, based on equivalent saturable absorber, 1μm band passively mode-locked fiber laser experiments are designed. The ultra-long resonant cavity of the mode-locked fiber laser at low repetition rate is detailed investigated, and rectangular pulses have been observed. By inserting a negative dispersion chirped-FBG in a long cavity structure, square optical pulse with fundamental frequency 221kHz and pulse width tuning range from 18.7ns-98.5ns is obtained. After being amplified, the output power is increased to 130W at the degree of polarization larger than 18dB. Secondly, through a combination of band-pass filter and Loyt filter, the tunable single-wavelength or dual-wavelength operation under dissipation soliton (DS) and dissipation soliton resonance (DSR) condition is generated in the long cavity based on the NPR structure, "step-like" rectangle pulse is observed and their formation is analyzed. In order to obtain ultrashort pulse of narrow spectral width at low repetition frequency, a acousto-optic modulator is added to pick the pulse , a stable pulse with pulse width of ~ 21ps and repetition rate tuning from 20KHz to 4MHz is obtained, and furthermore a preliminary amplification is carried on. The fourth chapter introduces 1μm passively mode-locked fiber laser experiments based on SESAM, the narrow linewidth (3dB spectral bandwidth <0.4nm) passively mode-locked fiber laser is assembled into a prototype. Four different devices including chirped fiber gratings, optical loop mirror, a bandpass filter or FBG and SESAM as the reflection mirror are combined to be investigated at different kinds of linear cavity configurations. Among them, by inserting FBG, a stable mode-locked narrow linewidth output with the center wavelength of 1030nm and pulse width of about 10.4ps which is near the limit of the conversion is observed in all polarization maintaining structure. Meanwhile, a research is conducted to achieve wavelength tunable and switchable fiber laser obtaining a stable pulse with a tuning range from 1022nm to 1061nm wavelength with narrow linewidth. The fifth chapter describes the experimental study on 2μm thulium-doped passively mode-locked fiber laser. Based on NPR effect and carbon nanotubes as the saturable absorber, ultra-short pulse is achieved in thulium-doped fiber laser. In both mechanisms wavelength-tunable phenomenon can be observed. Among them, the phenomenon of a dual-wavelength tenability is obversed in the mode-locked fiber laser based on carbon nanotubes and its causes are analyzed. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15979]  |
| 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 | 王兆坤. 超短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. 2016. |
| 个性服务 |
| 查看访问统计 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
修改评论