Patent ID: 7899331
Filing Date: 2011-03-01
Classification: H04J

Abstract:
1. A WDM optical transmission system which includes: a first optical amplifying section that amplifies a wavelength division multiplexed (WDM) signal light in which a plurality of optical signals of different wavelengths are multiplexed; an optical transmission path to which the WDM signal light amplified by said first optical amplifying section is input at one end thereof; and a second optical amplifying section that amplifies the WDM signal light output from the other end of said optical transmission path, comprising; a wavelength numbers detecting section that detects the number of wavelengths of the WDM signal light input to said first optical amplifying section, to create wavelength numbers information, wherein said first optical amplifying section includes: a first optical amplifier which amplifies the WDM signal light input thereto; a first signal output monitor which detects the total power of the WDM signal light output from said first optical amplifier, to create first signal output level information; a supervisory control light transmitter which transmits a supervisory control light containing the wavelength numbers information created by said wavelength numbers detecting section and the first signal output level information created by said first signal output monitor; and a multiplexer which multiplexes the WDM signal light amplified by said first optical amplifier with the supervisory control light transmitted from said supervisory control light transmitter, to feed the multiplexed light to the one end of said optical transmission path, and said second optical amplifying section includes: a demultiplexer which demultiplexes the light output from the other end of said optical transmission path into the WDM signal light and the supervisory control light; a second optical amplifier which amplifies the WDM light demultiplexed by said demultiplexer; a signal input monitor which detects the total power of the WDM signal light input to said second optical amplifier, to create signal input level information; a second signal output monitor which detects the total power of the WDM signal light output from said second optical amplifier, to create second signal output level information; a supervisory control light receiver which receives the supervisory control light demultiplexed by said demultiplexer, to acquire said wavelength numbers information and said first signal output level information; and a control circuit which computes a loss in said optical transmission path using the first signal output level information acquired in said supervisory control light receiver and the signal input level information created by said signal input monitor, to calculate a gain to be set for said second optical amplifier based on the computed loss, and also computes a target signal output level of said second optical amplifier using the wavelength numbers information acquired in said supervisory control light receiver, to correct said computed gain using a difference between said target signal output level and the second signal output level information created by said second signal output monitor as a correction value, to thereby control said second optical amplifier in accordance with the corrected gain.