Network node for a coherent optical wdm transmission network

Abstract

Provided is a network node for a coherent optical wavelength division multiplex (WDM) transmission network including at least one remote port which is adapted to receive from and/or output to neighboring network nodes an optical WDM signal including one or more optical channel signals each lying within an optical channel of an optical WDM transmission band and a predetermined number N of local ports, each local port being adapted to receive from a dedicated coherent optical transmitter an optical add channel signal which is to be integrated in an optical WDM signal that is output at a remote port and/or each local port being adapted to output to a respective dedicated optical receiver an optical drop channel signal. The network node includes an optical router device that defines the at least one remote port and further defines an internal remote port, the optical router device being configured to route one or more selected or all optical channel signals included in the optical WDM signal received at a selected remote port as optical drop channel signals to the internal remote port and/or to route one or more optical add channel signals received at the internal remote port to one or more selected remote ports or to all remote ports. The network node further includes a passive optical filter device which is connected, at an internal remote port of the passive optical filter device, to the internal remote port of the optical router device, and which further defines the predetermined number N of local ports. The passive optical filter device is configured to define N optical bandpass filter functions each of which describes a bandpass filter characteristic between the internal remote port of the passive optical filter device and a selected, respectively differing local port. The passband of each optical bandpass filter function covers two or more neighboring optical channels. The passbands of all optical bandpass filter functions differ from each other with respect to the optical channels covered.