Optical direct amplifier device

摘要

An optical direct amplifier device can detect failure of an excitation light source without using an electric circuit even when a monitoring system of the optical direct amplifier device based on a line turning back is employed. The optical direct amplifier device includes first and second optical amplifiers respectively amplifying signal lights of first and second transmission path. The optical direct amplifier device has a monitoring circuit branching only monitoring light wavelength of different from a wavelength of the signal lights and extracting means for extracting a part of an excitation light incided to the optical amplifiers.