【作者】 熊悦；

【导师】 潘炜；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2006， 硕士

【摘要】 高功率光纤激光器是集结了激光二极管光纤模块及其泵浦技术、双包层光纤制作技术及光纤光栅技术于一身的新型激光器技术,在通信、工业加工、军事、激光印刷、医疗等领域有着广泛的应用前景。近年来,双包层光纤激光器已成为国际激光界的一个研究热点。 本文概述了光纤激光器的发展历史、研究现状及发展方向,结合Yb³⁺离子的吸收及发射特性,建立了高功率掺Yb³⁺双包层光纤激光器（DCFL）的稳态速率方程模型,并数值模拟了泵浦吸收系数、泵浦方式、腔镜反射率和信号光损耗对DCFL输出特性的影响。分析结果表明:增加后腔镜泵浦反射率可以提高斜率效率;泵浦吸收系数对输出功率和光纤最佳长度有显著影响;而泵浦方式决定了腔内的功率密度和增益分布,采用多点泵浦可以使泵浦光在光纤中的分布更加平坦、均匀放大信号光,适用于超高功率光纤激光器件。 针对高功率激光器中泵浦光沉积所导致的热效应问题,由热传导方程分别得到DCFL内部温度的数值和解析解,并模拟分析了泵浦吸收系数、泵浦方式、光纤损耗系数、对流换热系数及内包层半径对激光器热效应的影响。结果表明:腔内温度沿径向变化很小,而沿轴向变化很大,在实际中可只考虑纤芯中心温度沿光纤轴向的分布;降低泵浦吸收系数可以明显改善DCFL的温度效应,但会引起输出功率的大幅度下降;两端泵浦时,随着后向泵浦功率的增加,腔内最高温度会出现最小值;增加内包层半径以及采取不同程度的制冷措施（风冷和水冷）可以降低DCFL的工作温度。 在分析研究高功率激光系统必须考虑的两个重要因素:输出特性和温度效应的基础上,通过优化增益光纤的分段数目、段长及各段上的泵浦功率,提出综合采用不均匀泵浦吸收系数和分段泵浦的方法,实现了输出功率与工作温度的最佳匹配,为高功率掺Yb³⁺ DCFL的优化设计提供了理论参考。更多还原

【Abstract】 High power fiber laser is a novel laser technology that combines LD fiber modules and its pump techniques, double-clad fiber fabrication technology and fiber grating techniques. Fiber laser has an important application foreground in many fields such as communications, industrial process, military affairs, laser printing, medical treatment, etc. Double-clad fiber laser has become a research focus in international laser domain recently.The history, recent research status and developmental direction are summarized in this paper. Integrated the absorption and emission characteristics of rare-earth-ions, the steady-state rate equations model of high power ytterbium doped double-clad fiber laser (DCFL) is established, and the influences of pump absorption coefficient, pump method, the reflectivity of pump power and signal loss on output characteristic are numerically simulated as well. The results indicate that the slope efficiency can be enhanced by increasing the reflectivity of pump power;pump absorption coefficient has great influence on output power and optimum fiber length;pump method decides power density and gain distribution in the cavity, moreover, adopting many-position pump can smooth pump power distribution and magnify signal power uniformly, suitable for super high power fiber laser apparatus.Aiming at thermal effect produced by the deposit of pump power in high power lasers, Numerical and analytical solutions of interior temperature in DCFL are obtained by the conductive equations, and the influences of pump absorption coefficient, pump method, fiber attenuation coefficient, convective coefficient and fiber radius are also analyzed. It is indicated that the temperature variation in radius can be neglected compared to axial direction;decreasing pump absorption coefficient can improve temperature effect obviously, but will also cause output power drop to some extent;along with the increase of backward pump in two-side end pump, the minimum value of maximum temperature in cavity will be obtained;increasing inner clad radius and adopting different cooling measures such as air and water cooling also can lower operating temperature in DCFL.Based on the research and analysis of two important factors that must be takeninto account for high power laser systems: output power and operating temperature, through the optimization of segment numbers, lengths and pump absorption coefficients in each segment, an approach under distributed pump and with nonuniform pump absorption coefficients is proposed to reach the best match of temperature distribution and output power, which provides the theoretical reference for optimization design in high power DCFL.更多还原