Progress on a cascaded optical link between Paris and Strasbourg

We are currently developing a cascaded optical frequency link between Paris and Strasbourg using the French National Research and Education Network RENATER. The ultrastable signal is copropagating with data traffic using wavelength division multiplexing. We have developed some repeater stations to amplify and filter the ultrastable signal between each sections of the link and compensate the propagation noise. The remote operation of these stations is a key element for the deployment of a reliable and large scale metrological network. We report on the first implementation of such a remote station on a 540-km cascaded link between Paris and Reims. The stability (modified Allan deviation with Λ-type counter) reaches a few 10−20 at 103 s averaging time.