Time Synchronization Over Cascaded Backbone and Access Fiber-Optic Links

We experimentally demonstrate a high-precision time synchronization system over a fiber-optic network with an equivalent 2400 km backbone link and a 60 km urban access link. Time signals aligned with the master station can be available at arbitrary station over the backbone and access links. Moreover, link calibrations are not required, which decreases the operation and maintenance cost significantly. The high-precision, easy-to-implement and telecom-network-compatible time synchronization system demonstrated here opens up a possibility to providing synchronized time signals to multiple users over the public telecom fiber networks.