Stabilized Time Transfer via a 1000-km Optical Fiber Link Using High-Precision Delay Compensation System

• DOI: 10.3390/photonics9080522
• Publication Date: 2022-07-28T07:21:16Z
• Authors: Bo Liu; Xinxing Guo; Weicheng Kong; Tao Liu; Ruifang Dong; Shougang Zhang
• Keywords: Time transfer; Optical link

Variations in optical fiber length and refractive index are induced by environmental perturbation, resulting an additional dynamic propagation delay fiber-based time synchronization systems, which deteriorate their transfer stability. This disadvantage can be significantly reduced transmitting the signal both directions through constructing a feedback loop to compensate at remote end of link. paper proposes analog-digital hybrid proportional integral derivative (PID) control compensation system based on time-frequency phase-locked (TF-PLL). The is designed keep merits wide servo bandwidth, accuracy, large range up 1 s, much greater than that reported previous studies. For proving validity this proposed scheme, self-developed equipment applied. used 1100-km long laboratory fiber, results show stability terms deviation (TDEV) less 5.92 ps/1 s 2.56 ps/10,000 s. After successful evaluation, installed real 988.48-km line between Xi’an Lintong branch National Time Service Center (NTSC) Linfen City, Shanxi Province, realizing 10 stations along experimental link illustrate measured difference with peak-to-peak value 176 ps, standard 19.3 TDEV 10.49 2.31 ps/40,000 achieved. high-precision simple, reliable, accurate; has compensation; opens feasible scheme for providing synchronized signals multiple users over long-distance field networks.