Circuit device for an amplifying fibre

摘要

Two input lines (22, 23) are switched (18) alternatively to a first wavelength-selective directional coupler (11) to which a pumping laser (9) is connected (10). The output lightguide (20) leads into the esp. Er-doped fibre (12) at whose far end second and third directional couplers (13, 14) are connected to a control unit (15) and an external optical network (6) respectively. Two output lines (24, 25) are selected by another switch (19) under the same control, which checks for the presence of an optical signal at the end of the fibre, and reverses both switches when necessary.