Level decline detecting apparatus, optical amplifier apparatus, and level decline detecting method

摘要

A first comparing unit compares the signal light level with a predetermined threshold value and outputs the comparison result to a signal decline notifying unit. A difference calculating unit subtracts the signal light level from a monitoring light level and calculates a level difference ΔP. A second comparing unit compares the level difference ΔP between the monitoring light and the signal light with a relative threshold value and outputs the comparison result to the signal decline notifying unit. If the comparison result of the first comparing unit indicates the signal light level is not more than the predetermined threshold value or if the comparison result of the second comparing unit indicates that the level difference ΔP is not less than the relative threshold value, then the signal decline notifying unit outputs to a control unit a decline warning indicating a decline in the level of only the signal light.