【作者】 江容容；

【导师】 郑义；

【作者基本信息】 郑州大学 ， 光学， 2011， 硕士

【摘要】 掺铥光纤激光器发射谱覆盖1.5μm至2.2μm波段,其中含有两个大气窗口和一个强水吸收峰,由于其波段位于人眼安全区,所以被广泛的应用于激光医学、遥感探测、激光雷达、军事等领域,是光纤激光器领域里的研究热点。本文从理论和实验方面对掺Tm3+双包层光纤激光器进行了研究。主要内容如下：1介绍掺铥光纤激光器的基本原理,归纳和阐述了双包层光纤激光器的关键技术。研究了铥元素的能级结构特点,对其光谱特性进行了分析,在此基础上介绍了掺Tm3+光纤激光器的三种泵浦方案3H6→3F4、3H6→3H5、3H6→3H4,并就三种泵浦方案的泵浦过程进行了分析。3H4能级在其泵浦波长处的吸收截面远大于3H5和3F4能级,3H6→3F4泵浦方案属于二能级系统,难以实现粒子数反转,而3H5能级存在激发态吸收,理论得出3H6→3H4的泵浦方案较优2理论上,从速率方程出发,建立了掺Tm3+双包层光纤激光器的理论模型,获得了激光器泵浦阈值功率和输出光功率的解析表达式。使用COMSOL软件模拟出光在光纤传输过程中的基模分布。在MATLAB仿真环境中,进一步分析泵浦光和信号光功率分布、光纤长度、后腔镜反射率、阈值功率、掺杂浓度以及泵浦结构对输出功率的影响。3实验上,对实心双包层光纤和光子晶体光纤端面进行研磨处理,并对比机器研磨和手工研磨两种技术,改进和提高相关实验操作技术。其次搭建和调试掺铥光纤激光器系统,采用前端泵浦技术,实现2.89W激光输出,斜率效率为27.5%,不稳定度为3.7%。更多还原

【Abstract】 Emission spectra of Tm3+-doped fiber laser which contains two atmospheric windows and a strong water absorption peak covers from 1.5μm to 2.2μm. Because the wavelength is safe to man’s eyes, it is being applied in many areas such as laser medicine, long-distance detective systems, laser radar, and military fields, and it is a new research focus in the fiber laser field.In this paper, Tm3+-doped double clad fiber laser is researched in theory and experiment. The main contents are summarized as follows:1 The basic theory of Thulium-doped fiber laser is introduced, and the key technologies of double-clad fiber lasers are introduced and elaborated. For the energy level structure of thulium, we researched the characteristic of it and analyzed the absorption spectrum, present three kinds of pump scheme of the Tm3+-doped fiber laser:3H6→3F4、3H6→3H5、3H6→3H4,and analysis the pumping process. The absorption cross section of 3H4 at the pump wavelength is larger than the others, the pumping scheme of 3H6→3F4 is hard to reverse the particle for it is two energy system, the energy 3H5 has excite state absorption, than, conclude that the pumping scheme 3H6→3H4 is more excellent.2. In theory, based on the rate equations, an analytical model of Tm3+-doped double clad fiber laser is developed, and the analytical expressions of output power and threshold pump power of fiber laser are obtained. The distribution and transmission of the fiber fundamental mode are simulated by the COMSOL software. The power distribution of pumping light and signal light in fiber, fiber length, rear cavity mirror reflectivity, threshold power, doping concentration and pump geometry which can influence the characteristic of the fiber laser are deeply investigated in the MATLAB simulation environment.3. In experiment, comparing the technology of hand-grinding with machine-polishing, end face of solid double-clad fiber and photonic crystal fiber are primarily grinded with the details of experimental operation technique being improved. The Tm3+-doped fiber laser with Fabry-Perot cavity is carried out, and the maximum output power obtained is 2.89W, and the slope efficiency is up to 27.5%, and the instability is 3.7%. The experimental results and some problems are reasonably analyzed, and then some ideas and suggestions are presented.更多还原