Inter-wavelength light power deviation monitoring method and optical equalizer and optical amplifier utilizing the method

An optical equalizer for equalizing wavelength characteristics of the light power of WDM signal light including a plurality of wavelength-division multiplexed channel light having wavelengths different from one another, said optical equalizer comprising:

• variable light-equalizing means having a variable light equalizing characteristic, to which is input said WDM signal light;
• channel information obtaining means for obtaining channel information concerning said WDM signal light;
• wavelength region setting means for setting, based on said channel information obtained by said channel information obtaining means, a plurality of measuring wavelength regions each including at least one distinctive channel light;
• light power measuring means for measuring channel light power of said WDM signal light passed through said variable light-equalizing means, for only said plurality of measuring wavelength regions set by said wavelength region setting means;
• and
• controlling means for obtaining, based on said channel information obtained by said channel information obtaining means, those target values of light power ratio for respective measuring wavelength regions, to flatten the light power wavelength characteristics of said WDM signal light and for obtaining measured values of light power ratio for the respective measuring wavelength regions, making use of the measured result of said light power measuring means, to control the light equalizing characteristic of said variable light-equalizing means so that said measured values become equal to said target values, respectively.

An optical amplifier incorporating optical amplifying means for collectively amplifying WDM signal light including a plurality of wavelength-division multiplexed channel light having wavelengths different from one another, said optical amplifier comprising:

• variable gain equalizing means having a variable gain equalizing characteristic, to which is input said WDM signal light;
• channel information obtaining means for obtaining channel information concerning said WDM signal light;
• wavelength region setting means for setting, based on said channel information obtained by said channel information obtaining means, a plurality of measuring wavelength regions each including at least one distinctive channel light;
• light power measuring means for measuring channel light power of said WDM signal light passed through said variable gain equalizing means, for only said plurality of measuring wavelength regions set by said wavelength region setting means;
• and
• controlling means for obtaining, based on said channel information obtained by said channel information obtaining means, target values of light power ratio for respective measuring wavelength regions, to flatten the light power wavelength characteristics of said WDM signal light, and for obtaining measured values of light power ratio for the respective measuring wavelength regions, making use of the measured result of said light power measuring means, to control the gain equalizing characteristic of said variable gain equalizing means so that said measured values become equal to said target values, respectively.

An optical amplifier incorporating:

• demultiplexing means for demultiplexing WDM signal light including a plurality of wavelength-division multiplexed channel light having wavelengths different from one another, into at least two amplification-wavelength bands, at least two optical amplifying means for amplifying optical signals of said respective amplification-wavelength bands, which are demultiplexed by said demultiplexing means, and multiplexing means for multiplexing respective optical signals amplified by said respective optical amplifying means;
• said optical amplifier comprising:
• variable gain equalizing means, which has a variable gain equalizing characteristic and which is provided at the preceding stage of an input side of said demultiplexing means;
• channel information obtaining means for obtaining channel information concerning said WDM signal light;
• input power measuring means, for receiving a part of optical signals of said respective amplification-wavelength bands to be input into said respective optical amplifying means, to measure the total input-light power into said respective optical amplifying means;
• and
• controlling means for obtaining, based on said channel information obtained by said channel information obtaining means, target values of total input-power ratio for respective optical amplifying means, to flatten the light power wavelength characteristics of said WDM signal light and for obtaining measured values of total input light power ratios for said respective measuring wavelength regions, making use of the measured result of said input power measuring means, to control the gain equalizing characteristic of said variable gain equalizing means so that said measured values become equal to said target values, respectively.