Patent ID: 8121486

Claim:
An optical transmission apparatus for adjusting optical intensity of wavelength-multiplexed signal light so as to relay the intensity-adjusted wavelength-multiplexed signal light between optical transmission paths, comprising: an optical attenuator whose attenuating amount is variable, for attenuating optical intensity of wavelength-multiplexed signal light received from the optical transmission path; a first optical intensity monitoring unit for demultiplexing an optical signal having a certain wavelength from the wavelength-multiplexed signal light passed through said optical attenuator so as to monitor optical intensity of said demultiplexed optical signal; a second optical intensity monitoring unit for branching a portion of the wavelength-multiplexed signal light passed through said optical attenuator so as to monitor optical intensity of the branched wavelength-multiplexed signal light; an optical amplifier for amplifying a portion of the wavelength-multiplexed signal light; a third optical intensity monitoring unit for branching a portion of the amplified wavelength-multiplexed signal light outputted from said optical amplifier so as to monitor optical intensity of said branched wavelength-multiplexed signal light; and a control unit for controlling the attenuating amount of said optical attenuator in such a manner that the optical intensity of the optical signal monitored by said first optical intensity monitoring unit is approximated to a first target value, and for controlling a gain of said optical amplifier in such a manner that a ratio of the optical intensity of said wavelength-multiplexed signal light monitored by said second optical intensity monitoring unit to the optical intensity of said wavelength-multiplexed signal light monitored by said third optical intensity monitoring unit is approximated to a second target value; wherein: said control unit divides the optical intensity of said wavelength-multiplexed signal light monitored by said second optical intensity monitoring unit by a total wavelength multiplexing number so as to calculate intensity of signal light per 1 wavelength; said control unit calculates a difference between the intensity of said signal light per 1 wavelength and a third target value; and said control unit updates said first target value based upon said calculated difference.