【作者】 尚连聚；

【导师】 宁继平；

【作者基本信息】 天津大学 ， 物理电子学， 2007， 博士

【摘要】 全光纤激光器具有效率高、结构紧凑和携带方便等优点,在军事、工业、生物医学、非线性频率变换、遥感和空间通讯等领域有广阔的应用前景,它的研究已成为激光器件领域内非常活跃的方向。本论文在理论方面研究了连续和调Q光纤激光器的工作特性,在实验方面设计成功了连续和调Q掺镱全光纤激光器。本论文的主要内容如下:1.首次从泵浦光和信号光功率分布的角度比较了不同泵浦方式和输出方式对连续光纤激光器综合指标的影响。重点研究了单端泵浦单端输出的特性,求解了描述纤芯内正向和反向功率分布的耦合波微分方程,计算了输出功率依赖于泵浦功率、纤芯直径、光纤长度和输出端反射率的定量关系,得出了连续光纤激光器输出特性的普遍规律;结论对连续光纤激光器的设计有指导意义。2.实现了连续掺镱全光纤激光器的实验运转。自行设计了泵浦源的温度控制系统,获得了波长为1083nm的连续激光输出,激光功率达到3.426W,半导体泵浦光转化为激光的效率为28.5%。3.首次提出了一种基于‘能量利用率与初始反转粒子数的关系’求解剩余反转粒子数的新方法,该方法简化了调Q光纤激光器数值计算的过程。在此基础上,根据调Q光纤激光器的速率方程理论,得出了调Q光纤激光器的初始参数诸如泵浦功率、纤芯直径、光纤长度、输出透过率和腔的固有损耗等影响脉冲宽度和脉冲能量的规律,进一步明确了压缩脉冲宽度和提高脉冲能量的方法;文中的分析可为同类调Q光纤激光器的设计提供参考。4.首次在国内开展了声光调Q掺镱全光纤激光器的实验研究。在连续掺镱全光纤激光器的基础上,谐振腔的高反端串接一个带尾纤的声光Q开关,实现了声光调Q掺镱全光纤激光器的实验运转;在重复频率500Hz时,脉冲宽度为3μs,脉冲能量达到2.94mJ;并实现了重复频率在10Hz-100kHz范围内可调。5.首次利用光纤型声光Q开关和单模光纤中的SBS效应进行了混合调Q掺镱全光纤激光器的实验研究。在重复频率50kHz时获得了脉冲宽度150ns的稳定脉冲输出。6.开展了被动调Q掺镱全光纤激光器的实验研究。利用单模光纤中的SBS效应实现了被动调Q掺镱全光纤激光器的实验运转,在重复频率30MHz时获得了脉冲宽度17ns的窄脉宽输出,实验结果处于国内较高水平。利用多模光纤中的SBS效应;在重复频率50kHz时获得了脉冲宽度2μs的脉冲输出。更多还原

【Abstract】 The all-fiber lasers have many merits, which include high efficiency, compact size and its portability. They are very attractive sources because of their wide applications in military affairs, industry, biomedicine, nonlinear frequency conversion, remote sensing and space communication, etc.This research makes a theoretical study of the characteristics of the CW fiber laser and the Q-switched fiber laser, and then offers a successful design of both the CW Yb³⁺-doped all-fiber laser and the Q-switched Yb³⁺-doped all-fiber laser. The main contents of this research are as follows.1. The comprehensive performance of the CW fiber laser with different pumping and output style is compared firstly from the perspective of the pump light and the signal light distribution. And the performance of the CW fiber laser with one-end pumping and one-end output style is studied mainly. The governing differential equations which describe the forward power and the backward power distribution inside the fiber core are solved. The quantitative relationship that the output power depends on the pump power, the fiber core diameter, the fiber length and the output reflectivity is worked out. So the general law about the output characteristics of the CW fiber laser is obtained. And the conclusions of this chapter are helpful to the design of the CW fiber laser.2. The operation of the CW Yb³⁺-doped all-fiber laser is realized. The cooling system used to control the temperature of the diode-laser is designed independently. During the experiment, the continous laser output of the Yb³⁺-doped all-fiber laser, whose wavelength is 1083nm, is achieved. The output power of 3.426W is obtained, and the optical to optical conversion efficiency reaches 28.5%.3. A novel method based on ’the relationship between the energy utility ratio and the initial particle inversion’ to solve the final particle inversion remaining is advanced firstly. And this method simplified the numerical calculation procedure of the Q-switched fiber laser. According to the rate-equation theory of the Q-switched fiber laser, the general law that some important initial parameters such as pump power, fiber core diameter, fiber length, output transmittance and fiber inherent loss influence the pulse width and the pulse energy is worked out, with the methods to narrow the pulse width and to improve the pulse energy clarified. The analysis of this chapter is of important reference to designing the kindred Q-switched fiber lasers.4. The experimental study about the acoustooptic Q-switched Yb³⁺-doped all-fiber laser is developed firstly in China. On the base of the CW Yb³⁺-doped all-fiber laser, a pigtailed acoustooptic Q-switch is inserted between the totally reflected FBG and the combiner’s signal port. During the experiment, the operation of the acoustooptic Q-switched Yb³⁺-doped all-fiber laser is realized. The 3μs pulse width and the 2.94mJ pulse energy are obtained at the repetition rate of 500Hz, and the repetition rate can be adjusted continuously between 10Hz and 100kHz.5. By firstly using the pigtailed acoustooptic Q-switch and the Stimulated Brillouin Scattering （SBS） effect of single-mode fiber simultaneously, the experimental study of the compoundly Q-switched Yb³⁺-doped all-fiber laser is accomplished, and a stable 150ns pulse width is obtained at the repetition rate of 50kHz.6. The Experimental study of the passively Q-switched Yb³⁺-doped all-fiber laser is developed. The operation of the passively Q-switched Yb³⁺-doped all-fiber laser is realized by adopting only the SBS effect of the single-mode fiber. And the narrow pulse width of 17ns is obtained at the repetition rate of 30MHz. Furthermore, by using the SBS effect of the multi-mode fiber, the 2μs pulse width is obtained at the repetition rate of about 50kHz.更多还原