Random lasers are a type of lasers that lack typical resonator structures, offering benefits such as easy integration, low cost, and low spatial coherence. These features make them popular for speckle-free imaging and random number generation. However, due to their high threshold and phase instability, the production of picosecond random lasers has still been a challenge. In this work, we have developed three dyes incorporating polymer optical fibers doped with various scattering nanoparticles to produce short-pulsed random fiber lasers. Notably, stable picosecond random laser emission lasting 600 ps is observed at a low pump energy of 50 µJ, indicating the gain-switching mechanism. Population inversion and gain undergo an abrupt surge as the intensity of the continuously pumped light nears the threshold level. When the intensity of the continuously pumped light reaches a specific value, the number of inversion populations in the “scattering cavity” surpasses the threshold rapidly. Simulation results based on a model that considers power-dependent gain saturation confirmed the above phenomenon. This research helps expand the understanding of the dynamics behind random medium-stimulated emission in random lasers and opens up possibilities for mode locking in these systems.

为了减弱激光二极管端面泵浦固体激光器热效应的影响，提高激光谐振腔稳定性及改善激光器的输出特性，以激光二极管端面泵浦Er:Yb:glass/Co:MALO晶体为研究对象，采用有限元分析方法，并根据热传导理论对其进行多物理场耦合热效应分析，系统分析了非键合和键合晶体、泵浦中心波长、功率以及束腰半径对激光晶体的温度场、热应力场以及形变量的影响。结果表明：键合晶体中Co:MALO晶体不仅起到了被动调Q的作用，还起到了热沉的效果，可以有效改善晶体内部的温度分布、热应力和形变量。中心波长为940 nm的泵浦对晶体的穿透性远高于976 nm，采用940 nm的泵浦可以改善晶体的最高温度，但976 nm泵浦结构是扩散键合较安全的结构。由于增大泵浦功率会导致晶体单位面积功率密度分布的增加，热效应也会加剧，泵浦功率增大100 mW对应温度增加9 K，热应力增加1.5 MPa，热形变增加0.5 μm。减小泵浦光束半径也会导致热效应的增加，但影响相较于功率不明显。理论分析结果可为激光二极管端面泵浦铒镱共掺磷酸盐玻璃1.5 μm固体激光器减小热效应的合理优化设计提供数据理论支持。

使用一种新型有机材料马来酸掺杂聚苯胺作为可饱和吸收体，在掺铒全光纤激光振荡器中实现稳定的调Q运转。实验中，采用双臂探测法测得该材料的调制深度和可饱和吸收强度分别为13.9%和0.336 MW/cm²，将其以薄膜三明治形式插入到光纤谐振腔中，最终获得了重复频率从33.78 kHz到87.01 kHz的范围内可调，最窄脉冲宽度为2.29 μs，最大单脉冲能量为54.64 nJ的稳定调Q脉冲输出。马来酸掺杂聚苯胺可以被认为是脉冲光纤激光器应用及其它光电器件的良好候选者。