Patent ID: 7170673

Claim:
An optical repeater apparatus wherein the apparatus comprises: an input port to which a plurality of light signals multiplexed in wavelength are inputted, a first fixed-gain optical amplifier for amplifying the wavelength-multiplexed light signals inputted through said input port with a predetermined gain, an optical demultiplexer connected to output of said first fixed-gain optical amplifier for demultiplexing said wavelength-multiplexed light signals into a plurality of individual light signals of respective wavelengths, one or more adjustable optical attenuators attenuating the outputs of said optical demultiplexers, respectively, by a predetermined factor, one or more fixed-gain optical amplifiers for amplifying said plurality of light signals outputted from said adjustable optical attenuators with a predetermined gain, monitoring light branching devices connected to outputs of said one or more fixed-gain optical amplifiers for extracting parts of specific monitoring light signals respectively, an optical multiplexer for multiplexing the outputs of said one or more fixed-gain optical amplifiers to thereby output multiplexed light signals, and one or more adjustable attenuator control circuits for detecting output powers of said monitoring light branching devices to thereby control the attenuation factor of said optical attenuators so that each of said detected output powers assumes a constant value.