An approach for frequency division of an optical pulse train (OPT) based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator (MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.

脉冲时域相干合成技术主要通过对功率放大后的高重频脉冲序列进行时序合成，从而降低激光的重复频率，有效地提升输出脉冲的峰值功率与能量，避免放大过程中高峰值功率引起的非线性效应。该技术与空域相干合成相结合，能够突破单纤激光的性能极限，实现高能量、高平均功率和高峰值功率的超短脉冲激光输出，具有广阔的应用前景。介绍了超短脉冲光纤激光时域相干合成的基本原理和关键技术，综述了时域相干合成系统的发展历程及其关键技术的研究现状，重点介绍了近年来脉冲分割放大与脉冲相干堆积技术的研究进展，并对时域相干合成的不同技术路线进行了分析与比较，最后对其未来的发展方向进行了梳理，为相关领域的研究提供参考。

The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility. Although each beam intensity is below its individual threshold for stimulated Brillouin backscattering (SBS), collective behaviors are excited to enhance the octad SBS. In particular, when two-color/cone lasers with wavelength separation 0.3 nm are used, the backward SBS reflectivities show novel behavior in which beams of longer wavelength achieve higher SBS gain. This property of SBS can be attributed to the rotation of the wave vectors of common ion acoustic waves due to the competition of detunings between geometrical angle and wavelength separation. This mechanism is confirmed using massively parallel supercomputer simulations with the three-dimensional laser–plasma interaction code LAP3D.

多芯光纤（MCF）是空分复用（SDM）技术的重要传输介质，能够数倍地拓展现有单根光纤的通信容量，然而MCF结构复杂度高、测试难度大，尚无测试标准。文章根据MCF的结构特点，结合在MCF开发中的技术经验，规范了MCF的熔接方法以及主要参数的测试方法，为未来MCF的大规模商用化奠定了基础。

空芯反谐振光纤（HCARF）的科学研究取得了突破性进展，其有望突破现有传统光纤的一些固有本征限制。HCARF将光束缚在空气芯中，在传输及其应用上具有传统光纤不可比拟的优势，因此，HCARF成为当前光通信领域的研究热点。文章介绍了HCARF的导光机理，并分析了其在光纤通信系统中的容量优势，阐述了HCARF的发展机遇与面临的挑战，希望能够为我国下一代通信大容量超宽带长距离传输光纤提供一定的参考价值与借鉴。

Broadband low-coherence light is considered to be an effective way to suppress laser plasma instability. Recent studies have demonstrated the ability of low-coherence laser facilities to reduce back-scattering during beam–target coupling. However, to ensure simultaneous low coherence and high energy, complex spectral modulation methods and amplification routes have to be adopted. In this work, we propose the use of a random fiber laser (RFL) as the seed source. The spectral features of this RFL can be carefully tailored to provide a good match with the gain characteristics of the laser amplification medium, thus enabling efficient amplification while maintaining low coherence. First, a theoretical model is constructed to give a comprehensive description of the output characteristics of the spectrum-tailored RFL, after which the designed RFL is experimentally realized as a seed source. Through precise pulse shaping and efficient regenerative amplification, a shaped random laser pulse output of 28 mJ is obtained, which is the first random laser system with megawatt-class peak power that is able to achieve low coherence and efficient spectrum-conformal regenerative amplification.