Patent ID: 8428463

Claim:
A method comprising: supplying a plurality of optical signals to an optical circuit, each of the plurality of optical signals having a corresponding one of a plurality of wavelengths; identifying a plurality of power levels at an input to the optical circuit; smoothing the power levels, a lowest power level being one of the plurality of the smoothed power levels that is less than remaining ones of the plurality of power levels; determining a plurality of target attenuations, each of which corresponding to a difference between a corresponding one of the plurality of power levels and the lowest power level, each of the plurality of target attenuations corresponding to a respective one of the plurality of optical signals; determining a plurality of attenuation errors, each of which corresponding to a difference between a corresponding one of the plurality of target attenuations and a respective one of a plurality of cumulative attenuations, each of the plurality of cumulative attenuations corresponding to an amount a corresponding one of the plurality of optical signals has been attenuated over a period of time, each of the plurality of attenuation errors corresponding to a respective one of the plurality of optical signals; attenuating selected ones of the plurality of optical signals, such that the plurality of power levels are substantially equal after said attenuating, the selected ones of the plurality of optical signals being associated with a sub-group of the plurality of attenuation errors, each attenuation error in the sub-group of the plurality of attenuation errors having a value greater than 0 dB.