水下无线光通信（UWOC）是一种新兴的高速水下通信技术，因其拥有传输带宽高、抗电磁干扰能力强、功耗低和体积小等优点，在学术界和工业界逐渐引起广泛关注。尽管光作为信息载体在水下传输时存在较大衰减，但其传输距离仍然可达百米级别，足以满足传感器数据传输的距离要求。然而，目前UWOC技术仍处于早期发展阶段，大部分UWOC系统的实验仅在实验室水箱开展，且性能测试方法各不相同，缺乏统一的性能测试模型和方法。为更客观地评估UWOC系统的性能，文章尝试提出UWOC系统的一般测试方法，建立测试模型，并总结系统评价指标，以促进UWOC技术的发展。

针对自由空间光（FSO）通信系统易受大气湍流效应影响的问题，为降低系统在饱和湍流情况下的误码率（BER），并且考虑到实际工程中需要在有限信噪比（SNR）下得到最大的分集增益，需要对系统的分集性能进行研究，以得到分集增益与SNR和系统链路数量等参数的关系。文章选择采用多输入多输出（MIMO）技术，设计了基于正交振幅调制（QAM）的MIMO-FSO通信系统，分析了系统在负指数分布信道模型下的性能表现，推导出系统的BER计算公式与分集增益相关参数（如分集阶数（DO）、分集阶数增量（IDO）和收敛速度（SOC）等）的闭式表达式，并利用数学软件Matlab进行仿真实验，通过蒙特卡洛仿真来验证所推导公式的准确性。仿真结果表明，MIMO技术在不增加发射功率和接收孔径面积的情况下，可以大幅度降低FSO通信系统的BER，且在饱和湍流信道下，系统链路数量越多或湍流强度越低时，DO随SNR增长到理论最大值的速度越快。MIMO技术有效地抑制了大气湍流对系统的负面影响，大幅提高了系统性能。在条件允许的情况下，尽量使用多的发射机和接收机可以使得系统在有限SNR下获得的分集增益更高，但是也需要考虑到实际工程中的部署成本和安装难度来选择合适的链路数量。

This paper presents an improved method for imaging in turbid water by using the individual strengths of the quadrature lock-in discrimination (QLD) method and the retinex method. At first, the high-speed QLD is performed on images, aiming at capturing the ballistic photons. Then, we perform the retinex image enhancement on the QLD-processed images to enhance the contrast of the image. Next, the effect of uneven illumination is suppressed by using the bilateral gamma function for adaptive illumination correction. The experimental results depict that the proposed approach achieves better enhancement than the existing approaches, even in a high-turbidity environment.

为有效解决高精度视觉定位测量系统中激光随机散斑导致的光斑质心定位精度降低问题，对散斑机理及抑制方法进行研究。从激光光斑的成像过程分析了激光随机散斑出现的原因，并推导出空间中任意一点总波扰表达式。建立了成像介质吸光性、粗糙度和表面出射光信噪比与随机散斑强度的关系模型，得出增加成像介质粗糙度和吸光性来提高出射光信噪比，进而降低随机散斑强度的结论。通过改变成像介质的物理特性进行对比实验，获得光斑质心位置稳定性随成像介质物理特性变化的趋势，验证了关系模型的正确性。实验结果表明，当激光功率为50 mW时，选取吸光性强、粗糙度与厚度适中的成像介质作为成像靶面，激光光斑质心的提取精度稳定在0.04个pixel之内，实现了对激光散斑的抑制，提高了光斑质心的定位精度。

Broad-spectrum absorption and highly effective charge-carrier separation are two essential requirements to improve the photocatalytic performance of semiconductor-based photocatalysts. In this work, a fascinating one-photon system is reported by rationally fabricating 2D in-plane Bi₂O₃/BiOCl (i-Cl) heterostructures for efficient photocatalytic degradation of RhB and TC. Systematic investigations revealed that the matched band structure generated an internal electric field and a chemical bond connection between the Bi₂O₃ and BiOCl in the Bi₂O₃/BiOCl composite that could effectively improve the utilization ratio of visible light and the separation effectivity of photo-generated carriers in space. The formed interactions at the 2D in-plane heterojunction interface induced the one-photon excitation pathway which has been confirmed by the experiment and DFT calculations. As a result, the i-Cl samples showed significantly enhanced photocatalytic efficiency towards the degradation of RhB and TC (RhB: 0.106 min⁻¹; TC: 0.048 min⁻¹) under visible light. The degradation activities of RhB and TC for i-Cl were 265.08 and 4.08 times that of pure BiOCl, as well as 9.27 and 2.14 times that of mechanistically mixed Bi₂O₃/BiOCl samples, respectively. This work provides a logical strategy to construct other 2D in-plane heterojunctions with a one-photon excitation pathway with enhanced performance.