Patent ID: 7489876

Claim:
An optical amplifier device disposed on an optical transmission line, comprising: a coupler to divide a wavelength division multiplexed signal light input to the optical amplifier device; an amplifier to amplify a part of the wavelength division multiplexed signal light input to the optical amplifier device, received from the coupler; a wavelength information generating unit to analyze another part of the wavelength division multiplexed signal light input to the optical amplifier device, received from the coupler, and to generate wavelength information of a signal carried by the wavelength division multiplexed signal light; and a noise elimination unit to filter out noise from wavelength bands of the amplified wavelength division multiplexed signal light, while preserving the signal according to the wavelength information, wherein said noise elimination unit comprises an optical filter capable of selecting a plurality of transmission wavelengths independently, a control section controls said optical filter so that a signal light wavelength of the signal light is selected as a transmission wavelength, based on the wavelength information of the signal light, and the optical amplifier device further comprising correction control means for measuring an optical power which was not selected by said optical filter and eliminated, and judging a power of the noise light included in the transmitted light selected by said optical filter based on the measuring, to perform a correction control of an amplification factor of said optical amplifier in accordance with the judging.