Without discrete optical components influencing the fiber format, all-fiber mode-locked laser has tremendous potential practical applications due to its advantages of better stability, alignment free, and better compaction. All-fiber laser mode-locked by nonlinear polarization evolution (NPE) can obtain good performances in terms of pulse duration and spectrum. But the effective saturable absorption mirror can be overdriven at high peak power, which leads to multiple pulses, limiting the output pulse energy. And there is a trade-off between avoiding overdriving the NPE and ease of self-starting. In addition, the polarization of the pulse propagating in a long fiber is so sensitive to the environment vibration that it is difficult to implement a stable lone-time operation. All-fiber ring laser mode-locked by NPE alone is analyzed and realized. The simulation results show that even a polarization vibration of /38 can break the mode-locking completely. Experimentally, after carefully adjusting, singlepulse mode-locking is achieved with the spectrum centered at 1053.4 nm and a maximum pulse energy of 82 pJ. But the output parameters change continually during operating. After 60 min, the mode-locking is broken. The conclusion is obtained that instability and unreliability of self-starting are inevitable for such a laser. Here, we show significant improvements of the pulse energy, operating stability, and self-starting reliability from an all-fiber Yb-doped mode-locked fiber laser. The laser is mode-locked by NPE combined with chirped pulse spectral filtering (CPSF). In order to easily self-start and stabilize mode locking, a spectral filter is employed in the all-normal group velocity dispersion NPE cavity to provide additional amplitude modulation. Combined effects of NPE and CPSF result in desirable pulse output, desirable operating stability, and reliable self-starting simultaneously. Stable mode-locking centered at 1053 nm is achieved with a 3 dB spectral bandwidth of 9.1 nm and pulse duration of 17.8 ps. The average output power is 66.9 mW at a repetition rate of 15.2 MHz, corresponding to a pulse energy of 4.25 nJ. Especially, high operating stability and easily one-button self-starting are achieved simultaneously. The fluctuations of output parameters including pulse energy, pulse duration, and spectrum are within 0.3% during 150-min operation. Self-starting reliability is tested. The testing time lasts two weeks. During the two weeks, the laser is turned off and turned on 48 times by using a power supplying button, without any adjustment. And the re-turned on intervals change randomly. Each time, the mode-locking can start itself. The repeatabilities of output parameters including pulse energy, pulse duration, and spectrum are within 0.55%.

采用布拉格光纤光栅作为谐振腔,实现了 980nm半导体激光器端面泵浦下的双包层掺镱光纤激光器的连续和调Q运转.连续激光实验结果表明,在泵浦功率固定时,增益光纤存在激光输出功率最大情况下的最佳长度,当泵浦功率增大时,最佳增益光纤长度也随之增加.采用石墨烯分散液作为可饱和吸收体,插入增益光纤与布拉格光纤光栅之间,实现了光纤激光器的稳定被动调Q运转.当泵浦功率为2.87 W时,得到了最小脉冲宽度33 ns、重复率38.5 kHz的脉冲序列;随着泵浦功率进一步增大,出现不稳定的调Q锁模现象.

研究了一种单双波长可切换的线偏振掺镱双包层光纤激光器结构，腔内插入可以绕光轴方向旋转的立方体偏振分束器(PBS)进行偏振控制，实现单双波长的转换。激光谐振腔由高反射率的双色镜和较低反射率（10.2%）的保偏光纤布拉格光栅（PM-FBG）构成；由于保偏光纤光栅的偏振选择反馈作用增强了偏振烧孔效应，通过调节谐振腔内偏振分束器的旋转角度实现了激光的单双波长之间的切换。利用琼斯矩阵理论分析了偏振态与旋转角度的关系，其结果与实验结果吻合。实验中输出激光的双波长为1070.08 nm和1070.39 nm、功率为1 W、激光信噪比为48 dB、斜率效率为34%、3 dB带宽为0.02 nm。利用格兰汤姆孙棱镜对该激光的偏振特性进行了研究: 单波长运转时为线偏振激光，偏振度达13.37 dB；双波长运转时为正交偏振激光。

利用保偏光纤布拉格光栅（PM-FBG）和高反射率的双色镜构成激光谐振腔，以单模保偏双包层掺镱光纤为增益介质，实现了输出功率为1 W的稳定的双波长激光输出，该激光信噪比为48 dB，斜率效率为34%。利用拱梁调谐方法对输出光栅进行了拉伸和压缩调谐实验,实现的激光调谐范围为8 nm，且调谐过程中双波长的波长间隔变化很小。以格兰汤姆孙棱镜验证了该激光的偏振特性。

为了研究光纤激光器工作中的自发辐射现象，从掺Yb3+光纤的能级结构和速率方程出发，建立主振荡功率放大（MOPA）光纤激光器的数学模型，对系统内各参量进行了数值计算。分析结果显示：在抽运工作稳态条件下，放大器的系统储能和自发辐射受到抽运强度和粒子掺杂浓度的影响；对于低重复频率的脉冲信号，放大过程中的自发辐射非常严重。为了减弱自发辐射，将连续抽运换成适当脉宽的脉冲抽运，即在信号脉冲前进行一段能够刚好让上能级粒子数充分恢复的脉冲抽运，可以在不影响信号脉冲放大的前提下，明显削弱连续抽运情况持续存在的自发辐射。数值模拟表明该方法在适当的抽运脉宽和强度下是可行的，实验数据则较为完好地印证了计算结果。

报道了直接使用半导体激光器（LD）抽运Yb3+掺杂光纤，实现长波的激光发射。通过LD直接抽运Yb3+掺杂光纤，获得了1117 nm的激光，最大输出功率为208 mW，斜率效率为50.5%。输出光谱显示抽运光被全部吸收，放大的自发辐射（ASE）比激光小近50 dB。

介绍了光纤激光器的理论模型和结构组成，搭建了976 nm激光二极管(LD)泵浦的准连续输出双包层掺镱光纤激光器系统。制作了激光脉冲电源方波发生电路，该电源在脉冲工作模式下重频≤1 000 Hz，脉宽从10 μs~50 ms可调，占空比≤50%。分析了稀土掺杂双包层光纤的各项性能和能级系统，并实验研究了准连续掺镱双包层光纤激光器的输出特性。在最大泵浦功率为812 W，重频为50 Hz和脉宽为10 ms下，测得其最大脉冲输出功率为267 W。

采用改进化学汽相沉积结合溶液掺杂法制备了掺镱石英光纤预制棒，并研究了不同镱掺杂浓度下的吸收光谱和发光光谱.吸收光谱和发光光谱的强度随着YbCl3溶液浓度的增大而增强.在不产生失透的前提下，得到预制棒芯层能够掺杂的YbCl3溶液最大浓度为0.057 mol/L.

利用在腔内加入可调谐光纤光栅滤波器使“8”字形腔掺Yb3+光纤激光器在锁模状态下实现波长连续可调谐.实验中，在保证锁模状态稳定的情况下，通过调节可调谐光纤光栅滤波器，使激光器输出锁模脉冲的中心波长在1 047 nm～1 055 nm范围内连续调谐，重复频率稳定维持在4.9 MHz.在中心波长1 053 nm处，测得锁模脉冲输出平均功率为8.02 mW，光谱带宽1 nm，脉冲宽度为259.3 ps.这种“8”字形腔被动锁模光纤激光器在锁模状态下对波长连续可调谐，并可长时间稳定工作.

利用一种新型的环形石墨炉加热的改进的化学汽相沉积(MCVD)车床制作出了高吸收、低背景损耗单包层高掺Yb3+石英光纤, 并对其几何参数和吸收谱进行了测量、分析和讨论, 得出了高掺Yb3+石英光纤的制作要点在于高质量疏松层的制作的结论, 并分析了疏松层中掺P有助于提高掺Yb3+量的机理。制作出的高掺Yb3+单包层石英光纤样品在976 nm波长下的吸收可达594 dB/m, 而背景损耗只有0.1 dB/m。