Monitoring system with edf for monitoring fiber integrity in optical transmission systems

A method for monitoring fiber integrity in an optical transmission link,

• the optical transmission link comprising an active network element and a passive network element which are connected via an optical transmission fiber,
• the method comprising:
• outputting, at the active network element, an optical signal at a wavelength λ1 or within a wavelength range Δλ1 into the transmission fiber in a direction towards the passive network element, wherein the optical signal is either generated within the active network element or supplied to the active network element;
• controlling or measuring or determining, at the active network element, relative or absolute values of the optical power Pin|λ1 of the optical signal;
• amplifying, at the passive network element, the optical signal by a pumped erbium-doped fiber (EDF) and reflecting the optical signal to form a reflected optical signal, the reflected optical signal being guided back, through the optical transmission fiber, to the active network element;
• measuring, at the active network element, relative or absolute values PRX|λ1 of the optical power of an optical receive signal SRX|1 at a wavelength λ1 or within a wavelength range Δλ1 that is received at the active network element;
• and
• determining an evaluation parameter Reval that is essentially determined by the transmission characteristics of the optical transmission fiber by using measured values of the optical power PRX|λ1 of the optical receive signal SRX|1 and the optical power Pin|λ1 of the optical signal;
• and
• comparing the evaluation parameter Reval with a predetermined evaluation threshold value in order to determine the integrity of the transmission fiber.