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。

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。

同步抽运锁模是一种调制增益的锁模技术,就是调节抽运光的调制频率使之等于激光器纵模间隔的整数倍。通过对抽运光源半导体激光器的驱动电流进行正弦调制,实现了掺镱光纤激光器(YDFL)的同步抽运锁模。通过调整抽运激光器的调制频率,在相应于二次谐波锁模,4阶有理数谐波锁模条件下分别得到了较窄的脉冲输出。对重复频率625 kHz的二次谐波锁模脉冲序列,脉冲宽度小于20 ns,约为抽运光宽度的1/40;平均输出功率2.34 mW,能量转换效率约为5%。