Bidirectional optical amplifier circuit

摘要

Disclosed is a bidirectional optical amplifier circuit having a function that achieves reliable detection of reflections from an exposed end at low cost. Received optical power is detected; if the detected power is less than a prescribed discrimination level, it is then decided that the detected light is not received signal light but transmitted signal light sent in the direction opposite from it and reflected at an exposed fiber end, and the bias current for a laser diode in the opposite path is reduced to lower the optical output level of an EDF.