Time transfer over a 2061 km telecommunication fiber-optic network with single-fiber and two-wavelength approach

In this paper, we demonstrate the single-fiber and two-wavelength time transfer (SFTWTT) over a 2061 km field fiber loopback link network with a synchronous wavelength-division and time-division multiplexing access (WD-TDMA).This system utilizes wavelength-division multiplexing to avoid the impact of backscatter.In order to achieve high-precision time transfer, time-division multiplexing access is employed.This approach facilitates multiple bidirectional comparisons between local and remote devices.A digital phase-locked loop (PLL), which matches the bandwidth of the transfer system, and precision temperature control technology have been proposed to enhance the high stability of the fiber-optic time and frequency transfer system.The first on-site high-precision fiber-optic time transfer system exceeding 2000 km has been validated.Experimental results show that the stabilities of 5.6 ps@1 s and 3.1 ps@40,000 s can be achieved.The precision of time transfer over a 2061 km fiber-optic network, employing a single-fiber and two-wavelength approach, has been significantly enhanced.This study presents an average time difference of 52 ps across the distance, with a system uncertainty budgeted at 41.8 ps.This achievement signifies a substantial advancement in the realms of stability and reach for optical fiber time transfer, facilitating the development of a high-precision ground-based time service system.