Communication Network Element and Method of Mitigating an Optical Jamming Attack Against an Optical Communication System

A communication network comprising an optical link and a communication network element comprising:

• an optical path for an optical communication signal;
• a monitoring port arranged to output an optical monitoring signal;
• an optical splitter provided in the optical path, the optical splitter arranged to receive the optical communication signal and to split off a part of the optical communication signal to form the optical monitoring signal;
• and
• optical isolation apparatus connected between the optical splitter and the monitoring port, the optical isolation apparatus arranged to transmit the optical monitoring signal propagating towards the monitoring port and arranged to apply an attenuation, IA, to an attacking optical signal propagating from the
• of the attacking optical signal being transmitted to the optical path.

A method of manufacturing a communication network element, the method comprising:

• providing an optical path for an optical communication signal;
• providing a monitoring port arranged to output an optical monitoring signal;
• providing an optical splitter in the optical path, and arranging the optical splitter to receive the optical communication signal and to split off a part of the optical communication signal to form the optical monitoring signal;
• and
• connecting optical isolation apparatus between the optical splitter and the monitoring port, and arranging the optical isolation apparatus to transmit the optical monitoring signal propagating towards the monitoring port and arranging the optical isolation apparatus to apply an attenuation, IA, to an attacking optical signal propagating from the monitoring port towards the optical splitter to thereby prevent a substantial part of the attacking optical signal being transmitted to the optical path.