基于飞秒锁模激光的高精度自由空间频率传输研究

Frequency transfer based on femtosecond mode-locked laser over free-space with a good performance of highly-robust, low phase noise and simplicity, have received wide attention in the synchronization system. The turbulence, fluctuation and temperature drift in free-space link, and the nonlinear phase noise of optical/electronic devices will distort the signal, resulting in the decrease of precision of frequency transfer. Some unsolved scientific problems in high-precision frequency transfer over free-space will be studied deeply in our research. We will first reveal the mechanism of signal distortion and precision loss in fiber and free-space, and propose the compensation scheme; nest we will reveal the relation between the drift of beam direction and the relative intensity noise (RIN), and propose the stabilizing scheme; lastly we will analyze the resolution limitation of the conventional phase discriminators and propose the cancellation scheme. Based on these studies, we will carry out an outdoor high-precision frequency transfer experiments over 100 m free-space link with the resolution of sub-10 fs. This technique can be used in the Multi-station synchronization over free-space and synchronization between satellites or space stations.

基于飞秒锁模光的自由空间频率传输技术由于灵活性高、相噪低、系统简单等特性在时频同步领域获得了广泛关注。自由空间中的大气湍流、振动和温漂等效应，以及光/电器件的非线性相位噪声等都会使信号产生变形，严重降低了频率传输的同步精度。我们将对采用自由空间信道中频率传输实现极高同步精度的场合下存在的尚未解决的基础科学问题展开深入的研究：自由空间高精度频率传输中信号变形、精度损伤机理与补偿策略的研究；光束方位波动与相对强度噪声（RIN）的关系与光束稳定策略研究；高精度频率传输过程中限制鉴相分辨率的因素与抑制策略研究。最后完成室外大于百米级自由空间，基于飞秒锁模激光的亚十飞秒单向频率传输系统。该频率传输技术可应用于自由空间多站高精度同步或星间同步等场合。

基于飞秒锁模光的自由空间频率传输技术由于灵活性高、相噪低、系统简单等特性在时频同步领域获得了广泛关注。自由空间中的大气湍流、振动和温漂等效应，以及光/电器件的非线性相位噪声等都会使信号产生变形，严重降低了频率传输的同步精度。我们对采用自由空间信道中频率传输实现极高同步精度的场合下存在的尚未解决的基础科学问题展开深入的研究：自由空间高精度频率传输中信号变形、精度损伤机理与补偿策略的研究；光束方位波动与相对强度噪声（RIN）的关系与光束稳定策略研究；高精度频率传输过程中限制鉴相分辨率的因素与抑制策略研究。最后完成了基于飞秒锁模激光的阿秒级精度同步技术，完成室外大于百米级自由空间，时延波动达到飞秒级的频率传输系统。该频率传输技术可应用于自由空间多站高精度同步或星间同步等场合。