基于单光子探测的高精度长距离光纤双向时间比对  

Two-Way Time Comparison of High-Precision and Long-Distance Optical Fiber Based on Single Photon Detection

作　　者：付鑫宇 胡亮[1] 周子杰 陈建平[1] 吴龟灵[1] Fu Xinyu;Hu Liang;Zhou Zijie;Chen Jianping;Wu Guiling(State Key Laboratory of Advanced Optical Communication Systems and Networks,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学区域光纤通信网与新型光通信系统国家重点实验室,上海200240

出　　处：《光学学报》2023年第13期53-62,共10页Acta Optica Sinica

基　　金：国家自然科学基金(62120106010);浙江省领雁计划(2022C01156);上海市自然科学基金(22ZR1430200)。

摘　　要：在长距离光纤时间传递链路中,为了避免使用中继放大导致双向传输时延不对称以及引入附加的噪声,提出一种基于单光子探测的长距离光纤时间传递方案。将经过主端(从端)1 pulse/s时间信号控制的激光脉冲序列作为发送信号,利用从端(主端)具有极高探测灵敏度的单光子探测器接收到达信号,并基于双向时分复用同纤同波时间比对方案得到双向光纤链路传输时延变化,进而根据时间相关单光子计数和高斯拟合的数据处理方式得到两端之间钟差的时间稳定度。为了实现单光子探测器在门控模式下对长距离光纤实验系统的长期测试,设计并实现了外部触发门控工作方式下动态调整的触发控制系统。通过利用光纤链路传输时延变化量,实现对门控触发信号的控制。350 km单模光纤和对应长度的色散补偿光纤(链路总损耗约为100 dB)的时间传递系统实验结果表明,时间传递稳定度优于1.5 ps@1 s和0.4 ps@8192 s。所提方法为长距离高精度光纤时间传递提供了一种有效的解决方案。Objective With the continuous progress in science and technology,the performance of time and frequency standards have been constantly improved,which brings about higher requirements for the accuracy of time and frequency transfer technology.Optical fiber has the advantages of low loss,large bandwidth,high stability,and resistance to electromagnetic interference,and optical fiber networks have spread all over the world.Optical fiber time transfer has been recognized as an effective solution to long-distance and high-precision time transfer.When optical fibers reach a certain length,the regeneration and amplification of signals must be installed for boosting the signals'amplitude.Additionally,optical amplifiers will lead to asymmetric bidirectional transmission delays,and complex delay calibration must be carried out to meet the requirements of high-precision time transfer.At the same time,the signal-to-noise ratio(SNR)will gradually deteriorate with the increasing transmission distance,which will reduce the stability of time transfer.Based on the high sensitivity of single photon detectors,this paper proposes a non-relay long-distance optical fiber time transfer scheme based on single photon detection.The scheme not only does not require link calibration,which reduces the complexity of the experiment,but also ensures the symmetry of bidirectional transmission delays to improve the accuracy of time transfer.The dynamically adjustable external trigger control system is designed and implemented to achieve the gating mode of single photon detectors with low dark counts.Consequently,the detectors can continuously detect the time signals without the effect of transmission delay variations of the optical fiber link.Methods Optical fiber time transfer mainly includes one-way and two-way methods,and this paper adopts the two-way method to design the experimental scheme.The scheme employs the laser pulse sequence controlled by the local(remote)1 pulse/s time signal as the transmission signal and utilizes single photon detec

关 键 词：光纤 时间传递 单光子探测 双向时分复用 传输时延 

分 类 号：TN929.11[电子电信—通信与信息系统]