SFSW Time Transfer Over Branching Fiber-Optic Networks With Synchronous TDMA

In this letter, we design and demonstrate a single-fiber and same-wavelength (SFSW) time transfer over branching fiber-optic networks with a synchronous time-division multiple access. After pre-synchronization, the transmission collisions among multiple nodes over an SFSW link in branching fiber-optic networks are avoided in the time domain. The two-way time transfer between a master node and multiple slave nodes is then completed within each timing duration over the branching fiber-optic network. A $1\times8$ experimental system with a 50-km single-mode fiber in each sub-path is demonstrated. Experimental results show that the stabilities of better than 45 ps/s and 10 ps/d can be achieved. The measured average clock differences over two branches with a 50-km fiber are 58 and 73 ps, respectively, which are within the calculated expanded uncertainty (with the coverage factor of 2) of 103 ps.