【作者】 崔建华；

【导师】 苏红新；

【作者基本信息】 河北大学 ， 光学， 2007， 硕士

【摘要】 掺Yb3+光子晶体光纤激光器(PCFL)是较常规光纤激光器更优秀的光子源,它在诸多科技领域有着广阔的应用前景。本论文概述了双包层光子晶体光纤激光器的发展状况及发展前景。从光纤中Yb3+的激光能级结构和光谱特性、双包层PCF的基本结构、PCF激光器的基本结构和功率传输方程等方面讨论了掺Yb3+双包层PCFL的基本工作原理。依据速率方程理论,建立了掺Yb3+双包层光子晶体光纤激光器的理论模型,并利用Rounge-Kutta(龙格—库塔)算法编程,分别对未考虑Raman效应和考虑Raman效应两种情况下激光器的输出特性进行了数值模拟。未考虑Raman效应时,得出了PCFL光学腔内传输功率的分布情况、阈值泵浦功率、输出功率与PCF长度和输出镜反射率的关系以及泵浦功率与输出功率的关系；分析了考虑Raman效应时,PCF长度、纤芯横截面积、纤芯有效吸收系数及泵浦方式对双包层PCFL输出特性的影响,找到了减小Raman效应提高激光输出功率的途径。对掺Yb3+双包层PCFL的功率特性和光谱特性进行了实验研究。采用单端输出方式时,得到的最大激光功率为3.63W,光—光转换效率为30.0%,斜效率为35.1%,输出光谱呈现多波长的特性；采用前后向双端输出时,获得的最大输出功率为4.245W,光—光转换效率为35.1%,斜效率为44.1%,获得了单个波长输出,峰值位于1067.560nm左右。利用闪耀光栅对掺Yb3+双包层PCFL进行了外腔调谐,在近76.3nm (1035.425-1111.770nm)波长范围内实现了连续调谐激光输出；另外,对外腔调谐PCFL的偏振度进行了测量,发现不同泵浦功率下的激光偏振度均大于0.87。更多还原

【Abstract】 Yb3+-doped photonic crystal fiber lasers (PCFLs) are more excellent photon sources than conventional fiber lasers, and they have very wide promising applications in a good many technological fields. The developments and the prospects of double-clad PCFLs are reviewed in this paper. The principle of Yb3+ doped double-clad PCFLs are discussed in many aspects, such as the specific laser energy structure and spectrum characteristics of Yb3+doped in fibers, the basic structure of double-clad photonic crystal fiber and PCFL, and the power transmission equations. The theoretical models of Yb3+-doped double-clad PCFLs are developed based on rate equations, and the characteristics of Yb3+-doped double-clad PCFLs, considering Raman Effect and without Raman Effect, are numerically studied using a standard Rounge-Kutta method with MATLAB. Without considering Raman effect, the relationship between the parameters and the output characteristics of the fiber laser are investigated, which conclude the distribution of transmission power in the laser’s cavity, threshold pump power, the relation between output power and photonic crystal fiber length, the relation between output power and mirror reflectivity, and the relation between pump power and output power. Considering Raman Effect, the influences of photonic crystal fiber length, cross section of the fiber core, effective absorption coefficient of fiber core and pumping mode on the output characteristics of double-clad PCFLs are given, and the method of reducing Raman Effect to advance output power is found. The experimental study on the output power and spectra of Yb3+-doped double-clad PCFLs has been made. In the single end output manner, the maximum output is 3.63W, light-light efficiency is 30.0%, slope efficiency is 35.1%, and the output spectrum shows itself multi-wavelength. In the double ends output manner, the maximum output is 4.245W, the light-light efficiency is 35.1%, the slope efficiency is 44.1%, and single wavelength with a peak value at about 1067.560nm is obtained. Wavelength tunable output with a range up to 76.3nm(1035.425～1111.770nm) is realized in a Yb3+-doped double-clad PCFL based on an external cavity of Littrow configuration. In addition, the output polarization of the tunable Yb3+-doped double-clad PCFL is also studied, and the measured polarizations with different pumping power are all more than 0.87.更多还原