Simultaneous transmission of time-frequency and data with co-amplification over urban fiber links

We demonstrate a simultaneous transmission of time-frequency and data over a 160-km urban business network in Shanghai.The signals are transmitted through a cascaded optical link consisting of 48 km and 32 km,which are connected by an optical relay.The metrological signals are inserted into the communication network using dense wavelength division multiplexing.The influence of the interference between different signals has been discussed.The experimental results demonstrate that the radio frequency[RF]instability can reach 2.1 × 10-14 at 1 s and 2.3 × 10-17 at 10,000 s,and the time interval transfer of one pulse per second[1PPS]signal with less than 10 ps at 1 s is obtained.This work paves the way for the widespread dissemination of ultra-stable time and frequency signals over the communication networks.