Patent ID: 7142356

Claim:
A method for controlling a gain of a Raman fiber amplifier having M Raman pumps in an optical fiber system that supports N optical signal channels, the method comprising: (a) partitioning the N optical signal channels into K wavelength regions, wherein K is at least one; (b) determining a corresponding power variation for each wavelength region; (c) determining a corresponding pump power adjustment for each Raman pump using a predetermined function, the predetermined function relating the corresponding power variation for each said wavelength region to the corresponding power adjustment for each said Raman pump, the predetermined function corresponding to a linear relationship between the corresponding power adjustment and the corresponding power variation of each said wavelength region, the predetermined function comprising: Δ ⁢ ⁢ P L ⁡ ( j ) ≈ ∑ k = 1 K ⁢ T LL ⁡ ( j , k ) ⁢ Δ ⁢ ⁢ S L ⁡ ( k ) , wherein k corresponds to a k th wavelength region, wherein j corresponds to a j th Raman pump, ΔS L (k) corresponds to the corresponding power variation for the k th wavelength region as linearly scaled, ΔP L (j) corresponds to the corresponding pump power adjustment of the j th Raman pump as linearly scaled, and T LL (j,k) corresponds to a linear coefficient relating the corresponding pump power adjustment of the j th Raman pump and the corresponding power variation for the k th wavelength region; (d) adjusting each said Raman pump in accordance with the corresponding power adjustment; (e) configuring optical signal channels, wherein a signal power is different from a reference point only in the k th wavelength region; and (f) determining the linear coefficient T LL (j,k) by calculating ΔP L (j)/ΔS L (k).