Overview: Since the groundbreaking discovery of gravitational waves, the scientific community has fervently pursued the exploration of low-frequency gravitational waves to glean deeper insights into the cosmos. The inherent limitations of ground-based conditions, however, pose formidable challenges for detectors in capturing gravitational waves below the 1 Hz threshold. Consequently, the imperative has shifted toward the deployment of space-based gravitational wave detectors as the paramount solution for effective low-frequency gravitational wave detection. At the crux of space-based gravitational wave detection lies the pivotal role of spaceborne telescopes. Given the expansive transmission distances spanning magnitudes of 10⁹ m between celestial constellations, the demand for nanoradian-level precision in telescope pointing accuracy becomes non-negotiable. The concomitant necessity for high-precision measurements and calibration emerges as a prerequisite for achieving the exacting standards of pointing accuracy in spaceborne telescopes dedicated to gravitational wave detection. To ameliorate the deleterious effects of pointing deviations on gravitational wave detection, this study strategically optimizes key parameters, including microlens structures, detector selection, and algorithmic frameworks, thereby achieving a breakthrough in high-precision pointing deviation measurements. Leveraging a low-density microlens array with extended sub-aperture focal lengths enhances the spatial scale of the light spot within each sub-aperture. This, coupled with detectors boasting a high signal-to-noise ratio, synergistically elevates the pointing detection accuracy of each discrete lens. Moreover, the paper introduces an innovative, Hartmann principle-based methodology for high-precision pointing deviation measurements, deploying a spatially reused paradigm across multiple sub-apertures. By aggregating measurement results from diverse sub-apertures, the approach effectively mitigates the influence of assorted random errors on measurement accuracy, thereby markedly enhancing the precision of pointing deviation measurements. Illustrating the efficacy of these methodologies, the paper exemplifies their application within the ambit of the "Tianqin Plan" for space-based gravitational wave detection. Employing numerical simulations and factoring in the design parameters of the Hartmann sensor, the study performs a meticulous analysis of pointing deviation measurement accuracy. Comparative analysis between single sub-aperture and sub-aperture correlation reuse technologies reveals a compelling enhancement in measurement accuracy, approximating a sevenfold improvement with the latter. The pointing deviation measurement accuracy achieved through sub-aperture correlation reuse technology is quantified at approximately 18.81 nanoradians. Considering the optical magnification inherent in spaceborne telescopes, estimated at around 30 times, the resultant pointing deviation measurement accuracy reaches an impressive 0.62 nanoradians. This design precision significantly surpasses the stipulated 1 nanoradian accuracy requirement for ground-based gravitational wave pointing deviation measurements. As a prudential measure, the proposed design incorporates a substantial margin to accommodate potential accuracy diminution attributable to external perturbations during empirical testing.

50 Gbit/s无源光网络（PON）标准已趋于完善，后50 Gbit/s PON时代的技术标准尚属空白，亟待开展相关研究以推动整个产业链从系统、模块和芯片等方面提前进行布局。文章判断单波长200 Gbit/s速率和相干技术将会是继50 Gbit/s PON之后下一代PON系统的两大关键特征。单波长200 Gbit/s速率对运营商具备更大的吸引力，而强度调制/直接检测（IM/DD）技术难以持续满足200 Gbit/s速率下系统对Class C＋等级功率预算的要求，需要采用灵敏度更高的相干技术。然而PON系统是一种典型的点对多点（P2MP）拓扑架构，将相干技术下沉到PON还有许多关键技术需要攻克，其中，涉及PON系统设备和媒体访问控制（MAC）芯片的架构重构、相干PON光模块的单纤双向（Bi-Di）技术改造、突发模式的相干发送与接收技术以及相干PON系统的波长管控技术。时分复用（TDM）仍然是实现P2MP传输的推荐方式，在TDM基础之上可以叠加新的复用维度，例如子载波复用（SCM）。新复用维度的引入给PON系统带来了灵活性，但同时也增加了设计的复杂度，将会颠覆当前的PON系统架构。叠加了SCM的相干PON系统将不再采用数字化接口方式与光模块进行连接，光模块本身需要具备高度线性驱动和调制能力。此外，用户侧光模块需要具备瞬时开关能力，以避免对其他用户造成干扰，因此需要开发新型的支持突发控制功能的相干光芯片。考虑到上行P2MP的突发相干接收环境，需要从系统层面实现对多个用户激光器的波长管控，避免上行方向因多用户波长快速切换造成的局端频偏估算偏差问题。综上，将相干技术应用于PON将会是一个全新的复杂系统工程，难以直接继承现有相干系统架构，需要匹配P2MP的应用需求，从芯片、模块和设备多个方面实现技术创新。

光纤通信与大容量高频无线通信深度融合是未来第六代移动通信（6G）的核心技术底座，对于构建“沉浸式通信、泛在连接、通信人工智能（AI）一体化”等6G典型场景具有重要意义。文章梳理了优化光纤无线融合传输系统架构和提升频谱效率的主流技术及其实现方案，对研发团队在这些方面取得的部分进展进行了总结。首先，面向新一代沉浸式通信的大容量需求，借助商用数字相干光模块（DCO），提出了一种“光纤－无线－光纤”一体融合传输系统新型架构，率先完成了光子太赫兹100/200/400 GbE实时无线传输通信实验，最高实现了2×240.558 Gbit/s的线路速率；其次，面向覆盖范围广和灵活部署的应用场景，将数字副载波复用（DSCM）技术引入光纤无线融合接入系统，文章设计并搭建出同时支持最多32路固定宽带接入和32路W波段毫米波无线接入的点对多点（P2MP）100 Gbit/s相干无源光网络（PON），能够灵活调整速率且便于后续迭代升级；最后，面向通信AI一体化需求，提出了一种基于似然感知的矢量量化（VQ）变分自编码器（VAE），基于AI技术对光纤无线融合通信系统进行端到端优化，在无需太赫兹功率放大器的情况下，成功演示了净速率为366.4 Gbit/s的双偏振（DP）2×2多输入多输出（MIMO）太赫兹信号6.5 m无线传输和20 km标准单模光纤（SSMF）传输。上述技术在未来6G典型场景中具有巨大的应用潜力，此外，文章还从大容量、长距离、集成化和智能化等方向对超100 Gbit/s光纤无线融合传输技术进行了展望。

为了满足当前日益增长的通信容量需求，新型多载波光纤通信技术成为科研人员关注的焦点。文章回顾了近20年来传统正交频分复用（OFDM）在光纤通信领域的发展历程，梳理了近年来滤波器组多载波（FBMC）和通用滤波多载波（UFMC）在光纤通信领域的相关研究。自2016年以来，针对光通信中OFDM存在的问题，如：带外泄漏高、依赖循环前缀（CP），峰均功率比（PAPR）值过高和系统同步要求高等，国内外众多学者以新型多载波为突破口展开了研究。FBMC光通信具有旁瓣功率最低和频谱利用率高等特点，但是由于使用了偏移正交幅度调制（OQAM），对应的数字信号处理（DSP）算法需要针对虚部干扰重新设计。UFMC光通信具备强大的时间同步偏差容忍性，对频率偏移不敏感，可以复用OFDM的DSP算法，但也存在如何进一步抑制带外功率和降低计算复杂度等问题。最后，文章结合当前的研究现状，对下一代光纤通信系统的诉求提出了研究方向和建议。