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.

Friction plays a critical role in dexterous robotic manipulation. However, realizing friction sensing remains a challenge due to the difficulty in designing sensing structures to decouple multi-axial forces. Inspired by the topological mechanics of knots, we construct optical fiber knot (OFN) sensors for slip detection and friction measurement. By introducing localized self-contacts along the fiber, the knot structure enables anisotropic responses to normal and frictional forces. By employing OFNs and a change point detection algorithm, we demonstrate adaptive robotic grasping of slipping cups. We further develop a robotic finger that can measure tri-axial forces via a centrosymmetric architecture composed of five OFNs. Such a tactile finger allows a robotic hand to manipulate human tools dexterously. This work could provide a straightforward and cost-effective strategy for promoting adaptive grasping, dexterous manipulation, and human-robot interaction with tactile sensing.

随着人工智能、大数据、云计算、物联网、移动电子等的发展，传统的稀土离子掺杂单芯单模光纤放大器承载的光纤通信系统的传输容量已经逐渐接近香农极限，需要发展新型材料体系，以拓宽光纤通信系统的传输容量。相比于稀土离子，量子点具有较宽的发光带宽、可调波长的发光特性，且量子点的发光性质可以通过多种化学手段调控，在量子点光放大器上显示出了宽带光放大特性，受到学术界和产业界的广泛关注。在该背景下，本文提出将化学合成的PbS/CdS核壳量子点与低损耗聚合物集成，获得量子点掺杂光纤放大器，实现近红外通信波段可调波长、宽带光放大特性。文章研究并揭示了影响固化后的聚合物纤芯连续性的因素和影响机制，提出了降低固化胶前驱体液面附加压力、固化收缩力、聚合物前驱体与光纤内壁的摩擦力，并提高抽真空产生的牵引力以获得连续光纤，在此基础上获得了基于热固化聚二甲基硅氧烷（PDMS）和光固化NOA61、NOA85固化胶的纤芯连续光纤，量子点光纤在1 530~1 630 nm获得了增益带宽达到100 nm以上的开关增益，最高增益达到6.5 dB。本文的研究结果将促进量子点光纤器件和宽带光通信技术的发展。

基于全矢量有限元法，研究了聚合物中空环芯光纤结构的椭圆、偏芯、直径不均匀等几何形变对光纤中轨道角动量模式性能的影响；此外，还研究了在保持轨道角动量模式稳定传输的条件下，光纤结构所能承受的最大形变.结果表明椭圆和偏芯会引起轨道角动量模式在传输过程中发生奇偶模间的模式走离，导致轨道角动量模式纯度降低，进而导致模式串扰增大；数值计算结果表明，当椭圆度或偏心度小于1%时，模式纯度大于99.02%，串扰小于-20.08 dB.光纤的直径不均匀仅对光纤中所能支持的轨道角动量模式数量造成影响，纤芯半径越大，光纤中所能传输的轨道角动量模式越多；直径不均匀度在-3%~10%内的光纤均可支持原有的26个轨道角动量模式.