自由空间微波和光学频率同时传递技术研究

Simultaneous dissemination of microwave and optical frequencies over free-space have been widely used in basic scientific research fields and major national projects such as space-air-ground time-frequency reference, precision physical constant measurement s (e.g., fine structure constant), BeiDou navigation and so on. To combat the challenges of simultaneous dissemination of microwave and optical frequencies over free space, this project will conduct in-depth systematic research. In order to obtain an optimal method and system, the project will establish a theoretical modal by deeply analyzing the mechanism of the impact of atmospheric channels, in particular turbulence, on simultaneous dissemination of microwave and optical frequencies over free space. Moreover, it will provide a unified method of simultaneous dissemination of microwave and optical frequencies over free space with low complexity and high reliability. Key technologies with broadband coupling of microwave and optical frequencies and simultaneous compensation of phase noise for both frequencies will be adopted. By optimizing the proposed method and design, indoor and outdoor experiments will be performed. The implementation of this project will enable China to take the lead in the field of simultaneous dissemination of microwave and optical frequencies over free-space, and lay solid theoretical and technological foundations for promoting the development and application in space-air-ground time-frequency reference and other fields.

自由空间微波和光学频率同时传递在大型精密物理常数测量、天地一体时间频率基准、北斗导航等基础科学研究和国家重大工程领域有着重要的应用需求。国内外尚未有自由空间微波和光学频率同时传递的研究报道，本项目针对自由空间微波和光学频率同时传递面临的挑战，开展深入系统的研究。通过分析大气信道尤其是大气湍流对微波和光学频率传递影响的机理，建立自由空间微波和光学频率同时传递的理论模型；提出低复杂度、高可靠、一体化的高精度自由空间微波和光学频率同时传递方案；突破微波和光学频率信号的宽带电光耦合与相位噪声协同补偿机制等关键技术；优化微波和光学频率同时传递方案和系统设计，开展室内和现场实验。本项目的实施可以使我国占领自由空间微波和光学频率同时传递研究的先机，为推动天地一体时间频率基准等领域的发展与应用提供理论和关键技术支撑。

自由空间微波和光学频率传递在相干光通信、地基与天基射天天文学等基础物理科学研究以及北斗导航、国家时频体系建设等重大科学工程相关的众多研究领域有着广泛的应用。针对采用复杂并且昂贵的光学频率频率梳实现微波和光学频率同时传递的局限性。本项目实现的“自由空间微波和光学频率同时传递”的实施可解决现阶段中无低系统复杂度和低成本的自由空间微波和光学频率同时传递的科学难题，为推动相干光通信以及下一代基于光学频标的时频标准的发展与应用奠定坚实的科学基础。.项目组经过潜心研究和攻关，建立了自由空间微波和光学频率传递链路模型和自由空间大气湍流影响模型，形成了一套完善的光自由空间微波和光学频率传递系统优化设计及测试评估方法；在国际上首次提出被动相位噪声补偿光学频率传递方法，研究提出了对成本可移动自动跟瞄光学天线、低本底噪声系统方案等关键技术方案，解决了高精度快速大动态范围相位噪声补偿等关键问题，形成了完整独有的自由空间微波和光学频率传递技术体制，研制出系统设备样机，演示了公里级自由空间频率传递和460公里实地光纤链路频率传递、频率传递稳定度达到1E-19量级；完成了京雄高精度地基光纤授时、原子时频基准传递等多项应用测试与示范，验证了系统满足时间频率体系、通信网高精度基准参考、5G业务协同等应用的能力，可为国家重大基础设施、前沿科学研究及信息产业等的建设发展提供基础支撑。