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.

为了解决相位生成载波解调方案应用于激光测振技术时，系统中存在的非线性失真问题，提出一种改进相位生成载波解调算法。该算法采用低频、大幅值的相位调制和迭代重加权椭圆特殊拟合对两路含有非线性误差的正交信号进行校正以抑制非线性失真。其中，低频相位调制由三角波信号驱动压电换能器生成，确保小信号情况下椭圆拟合结果的准确性。迭代重加权椭圆特殊拟合可以减小离群数据的影响并避免拟合结果退化为双曲线，具有精度高、鲁棒性好和计算效率高的优点。实验结果表明改进相位生成载波解调算法可以有效抑制激光测振实验系统的非线性失真，在不同相位调制深度（0.8~3.4 rad）下解调信号的信纳比和总谐波失真稳定，对应的标准差分别为0.55 dB和0.03%。系统的响应线性度优于99.99%，动态范围可达103.9 dB @ 500 Hz，总谐波失真为1%且工作频宽为20~8 000 Hz。与传统相位生成载波解调方案相比，该算法不仅显著抑制了非线性失真，还克服了椭圆拟合算法在小信号下无法工作的缺点。

An imperfect propagation environment or optical system would introduce wavefront aberrations to vortex beams. The phase aberrations and orbital angular momentum in a vortex beam are proved to be mutually restrictive in parameter measurement. Aberrations make traditional topological charge (TC) probing methods ineffective while the phase singularity makes phase retrieval difficult due to the aliasing between the wrapped phase jump and the vortex phase jump. An interactive probing method is proposed to make measurements of the aberrated phase and orbital angular momentum in a vortex beam assist rather than hinder each other. The phase unwrapping is liberated from the phase singularity by an annular shearing interference technique while the TC value is determined by a Moiré technique immune to aberrations. Simulation and experimental results proving the method effective are presented. It is of great significance to judge the characteristics of vortex beams passing through non-ideal environments and optical systems.

为缓解基于可变形镜（DM）的自适应自由曲面干涉仪存在的固有矛盾——不能同时兼顾大动态像差补偿与DM形变监测范围，前期提出了循环利用DM形变量去产生大畸变波前的自适应环形补偿器（ARCC），并得到了初步验证。为了推广其在自由曲面自适应检测中的应用，并结合校正光学系统的自由曲面多为低阶像差面的现实问题，对ARCC的低阶像差补偿特性做出了必要验证和研究。首先，通过Zemax建模对比了ARCC和传统单次往返补偿器(TSRC)对于像散、彗差和球差的补偿能力，得出ARCC补偿像散和彗差的能力近似为TSRC的2倍，补偿球差的能力也要显著大于TSRC，验证了ARCC的低阶像差补偿优势；其次，研究了ARCC的低阶像差类型补偿规律，得出ARCC结构中DM上的像差类型与补偿给被测面的像差类型是“一对多”或“多对一”的关系。结果证明：在实际中分别使用ARCC和TSRC对4块低阶像差自由曲面进行补偿验证，同样的DM形变量下，与传统补偿结构相比ARCC展现出更加出色的低阶像差补偿能力。

变焦物镜是偏振成像系统的重要组成部分，目前因变焦物镜使用较多非球面而导致价格较为昂贵。为了降低偏振成像系统变焦物镜的加工成本，设计了一款用于偏振成像系统的20 mm~200 mm变焦物镜。采用正组补偿，利用Zemax优化变焦系统，最终系统仅使用7片球面透镜，并达到良好像质，系统调制传递函数（MTF）在120 lp/mm处大于0.3，畸变小于4%，系统凸轮曲线平滑无断点。系统公差分析结果表明，公差范围设置为：镜片表面光圈公差为2，镜片或空气中心厚度公差为±0.02 mm，透镜表面中心倾斜公差为±0.025°，透镜装调公差为±0.025 mm，透镜折射率偏差为0.002，公差设置符合元件加工和系统装调工艺，对降低偏振成像系统成本具有一定的参考价值。

随机激光器由于其独特的结构和低相干性，在无散斑成像、传感、光治疗等领域中得到广泛应用。随机激光器的反馈机制是无序介质引入的光散射，高阈值和无方向性是其主要缺点。为解决这些问题，研究者们利用光纤的一维束缚获得低阈值并有一定方向性的光纤随机激光。近十年来，随机激光的发展经历了从非相干反馈到相干反馈、从完全无序到输出参数可控的过程。大量研究尝试用量子理论、混沌激光理论和数值分析等方法来解释随机激光的物理本质。回顾了随机激光和光纤随机激光的起源和发展历史，介绍了随机激光的分类和相关原理，总结了调控随机激光输出参数的方法并展示了随机激光的新近典型应用，分析了光纤随机激光的反馈类型和增益机制，并在最后展望了随机激光未来的发展趋势。