US 8,428,463 B2 · Apparatus and method for controlling a dynamic gain equalizer

Abstract

Consistent with the present disclosure, a method and apparatus for providing a uniform spectral gain of an optical amplifier is provided. Namely, a “balancing” step is carried out in which an optical channel having the lowest power level input to an optical circuit, such as an dynamic gain equalizer (DGE), is assigned a zero “attenuation error” and is substantially un-attenuated by the DGE. The lowest power level optical signal does not require further attenuation and effectively serves as a reference power level, which the power levels of the remaining optical signals are set to. For example, remaining optical signals are assigned either positive or negative attenuation errors relative to the zero attenuation error based on optical signal input powers to the DGE and accumulated DGE attenuations over time. Those optical signals having a negative attenuation error are substantially unattenuated by the DGE, because such optical signals are adequately attenuated and do not require further attenuation. On the other hand, the DGE is controlled to attenuate those optical signals having positive attenuation errors to thereby flatten the output spectrum of the amplifier. In one example, interpolation techniques may be employed to control those portions of the DGE (e.g., attenuators or pixels) that do not receive a channel, such that adjacent pixels that receive channels may impart a desired amount of attenuation. In addition, further interpolation may be provided to appropriately control the DGE pixels, if the number of channels supplied to the DGE is different than the number of pixels of the DGE.

Claims22

Dependent claims

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.

3 more elements

An apparatus comprising:

an optical circuit configured to receive a plurality of optical signals and output the plurality of optical signals, each of the plurality of optical signals having a corresponding one of a plurality of wavelengths;
an optical power monitoring circuit configured to generate a plurality of sense signals, each of which being indicative of a corresponding one of a plurality of power levels, each of the plurality of power levels being associated with a corresponding one of the plurality of optical signals;
and
a processor circuit that:
identifies the plurality of power levels, a lowest power level being one of the plurality of power levels that is less than remaining ones of the plurality of power levels;
determines 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;
determines 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;
and
outputs a plurality of control signals, the optical circuit attenuating selected ones of the plurality of optical signals in response to the control signals, such that each of the plurality of power levels is substantially equal to one another 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.

6 more elements

Dependencies are inferred from the claim text.

Apparatus and method for controlling a dynamic gain equalizer

Life of this patent

Apparatus and method for controlling a dynamic gain equalizer

Life of this patent

Abstract

Claims22