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.

本文设计了一种以液晶聚合物为介质基板的频率可重构天线，通过调节贴片的位置及尺寸实现天线的阻抗匹配。制备聚合物分散液晶薄膜作为天线的介质，并根据液晶与聚合物的比例分别为7∶3、6∶4、5∶5这3种不同配比以及50 μm和100 μm两种不同膜的厚度来考察其效果。在电场作用下，液晶微滴会沿着电场方向重新取向排列，通过改变驱动电压的大小，实现天线的频率可重构。经过对比分析得出，液晶含量（质量分数）为70%的聚合物分散液晶薄膜具有最佳的效果，在48 V的驱动电压下实现了62 MHz的频率连续调节，天线的最大增益为3.5 dBi。该基于液晶聚合物的频率可重构贴片天线结构简单、体积小、质量轻，易于集成在各种移动设备中，发展前景广阔。

目前针对常见爆炸物三硝基甲苯 (TNT) 的检测越来越受到重视。本研究采用低成本的芴基发绿光共轭聚合物（FGEP）研制荧光淬灭传感器用于检测TNT。实验研究了FGEP在不同溶液浓度下形成的不同厚度薄膜对TNT淬灭的效率，实验结果表明浓度为0.5 mg/mL (厚度为19.50 nm) 的样品薄膜在TNT蒸气中淬灭效率最大达到71.71%, 基于此淬灭效率最高的样品薄膜的研究发现：该薄膜对TNT的响应具有良好的可逆性；激发光强度为16.5 mW时，荧光淬灭效率最佳；最后开展了样品在TNT作用下与光漂白作用下的实验研究。研究结果为后续实现一种低成本、易于制备、可重复性高且有利于工程化的爆炸物传感器提供了一定基础。

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.

聚合物稳定VA（PSVA）液晶显示模式具有优异的光电性能。为进一步提升PSVA显示模式的透过率，在液晶中加入手性剂，形成手性掺杂聚合物稳定VA（C-PSVA）液晶显示模式。本文对C-PSVA显示模式的最优参数及实际显示效果进行研究。首先，建立模型对C-PSVA显示模式的光电特性及液晶分布进行模拟，分析了手性剂的加入对液晶排列产生的影响，对C-PSVA的显示原理进行分析。其次，研究了C-PSVA显示模式的延迟量、偏光片角度、手性剂比例对透过率提升的影响。最后，按照模拟结果配制液晶，制作C-PSVA样品，进行实际效果验证。结果表明，C-PSVA显示模拟的透过率较PSVA显示模式有明显提升，C-PSVA显示模式最佳延迟量约为460 nm，最优手性剂含量对应螺距值为4倍的盒厚。实测结果显示，与PSVA显示模式相比，C-PSVA显示模式透过率约有13%的提升。