主动锁模掺镱光纤激光器的理论与实验研究

发布时间：2018-03-23 17:49

本文选题：主动锁模　切入点：掺镱光纤激光器　出处：《北京理工大学》2015年硕士论文

【摘要】：随着激光技术的飞速发展，脉冲激光器已经被广泛运用于医疗、工业加工、激光武器、激光可控核聚变等多个领域。相比于传统的固体激光器，光纤激光器有着增益特性好、转换效率高、易于和光纤耦合等特点，因此锁模光纤激光器成为了目前超快激光研究领域的一个热门研究课题，本文从理论和实验两个方面对锁模掺镱光纤激光器进行了具有一定深度的研究，，主要内容如下： 1．对于锁模掺镱光纤激光器及其国内外研究进展进行了文献调研，对比分析了各种设计方案的优缺点，在此基础上提出了自己的设计方案。 2．结合自己的设计方案，在忽略放大自发辐射（ASE）的情况下，从速率方程出发，推导出了环行腔和线型腔掺镱光纤激光器的增益、阈值功率、输出功率和斜效率的解析表达式。并且讨论了谐振腔关键参数（泵浦功率、掺镱光纤长度、输出耦合比）和激光器输出参数（输出功率、斜效率）之间的关系，并进行了数值分析，得到了最佳优化参数和激光器理论极限参数 3．针对使用相位调制器锁模带来的输出不稳定问题，从非线性薛定谔方程出发，建立主动锁模掺镱光纤激光器的数值模型，通过Matlab进行模拟仿真。通过逐步调整腔内平均色散大小，解决了输出激光脉冲的不稳定问题。在稳定锁模的基础上，进一步研究了激光器关键参数（色散、非线性、小信号增益系数、锁模阶数、调制深度）对于激光器输出脉冲特性（脉冲宽度、重复频率）的影响。仿真结果表明，激光器可以稳定的输出皮秒量级的高质量光脉冲，重复频率为4.9GHz，脉冲宽度为2.6ps，在理论上验证了本文设计方案的可行性，并且进行了结构和参数方面的优化，对于后续实验工作具有一定意义上的指导作用。 4.选购用于组成环行腔激光器的各项器件，搭建了主动锁模掺镱光纤激光器实验装置，通过调试在基频点处获得了锁模脉冲输出。本文设计方案的特色是使用了光子晶体光纤，通过在环行腔内加入光子晶体进行色散补偿，解决了输出脉冲不稳定问题，同时对输出光脉冲的脉宽进行了压缩。
[Abstract]:With the rapid development of laser technology, pulsed lasers have been widely used in medical treatment, industrial processing, laser weapons, laser controlled nuclear fusion and other fields. Compared with conventional solid-state lasers, fiber lasers have good gain characteristics. Because of its high conversion efficiency and easy coupling with fiber, mode-locked fiber laser has become a hot research topic in the field of ultra-fast laser research. In this paper, the mode-locked ytterbium-doped fiber laser is studied theoretically and experimentally. The main contents are as follows:. 1. Based on the literature investigation of mode-locked ytterbium-doped fiber laser and its research progress at home and abroad, the merits and demerits of various design schemes are compared and analyzed. Based on this, the author puts forward his own design scheme. 2. Based on the rate equation, the gain and threshold power of ytterbium-doped fiber laser with annular cavity and linear cavity are derived under the condition of neglecting the amplified spontaneous emission (ASE). The relationship between the key parameters (pump power, ytterbium-doped fiber length, output coupling ratio) and laser output parameters (output power, skew efficiency) is discussed. The optimum optimization parameters and the theoretical limit parameters of the laser are obtained by numerical analysis. 3. Aiming at the output instability caused by mode-locking of phase modulator, a numerical model of active mode-locked ytterbium-doped fiber laser is established based on nonlinear Schrodinger equation. Through Matlab simulation, the instability of output laser pulse is solved by adjusting the average dispersion in cavity step by step. The key parameters (dispersion, nonlinearity) of laser are further studied on the basis of stable mode-locking. The effects of small signal gain coefficient, mode-locking order, modulation depth on the output pulse characteristics (pulse width, repetition rate) of the laser are discussed. The simulation results show that the laser can output a high quality optical pulse of picosecond order. The repetition rate is 4.9 GHz and the pulse width is 2.6 ps.Therefore, the feasibility of the design is verified theoretically, and the structure and parameters are optimized. 4. The experimental device of active mode-locked ytterbium-doped fiber laser is built, and the output of mode-locked pulse is obtained at the fundamental frequency point by debugging. The characteristic of the design is that the photonic crystal fiber is used to compensate the dispersion of the output pulse by adding the photonic crystal in the ring cavity, and the pulse width of the output pulse is compressed.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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