Frequency distribution in delay-stabilized optical DWDM network over the distance of 3000 km

In the paper we are presenting the results of the experiments we performed with sending the frequency signals (10 MHz) to the remote location exploiting the optical dense wavelength division multiplexed telecommunication network. To stabilize the phase of the frequency signal we applied the approach with the electronic stabilization of the propagation delay. We measured the residual instability resulting from the fact that in a telecommunication network the signals in the forward and backward direction do not share the same fiber and are transmitted through different pieces of equipment when passing through reconfigurable optical add drop multiplexers or optical amplifiers. Our experiments show that results may depend substantially on the route of the link. For all tested links, however, the stability was better than the stability of the signal generated by commercial 5071A cesium standard. In case of one link even the stability better than stability of H-maser was observed for averaging times longer than 1000 s.