Fast dynamic gain control in an optical fiber amplifier

A Raman fiber amplifier that supports N optical signal channels in an optical fiber system, comprising:

• M Raman pumps, each Raman pump injecting optical power into an optical fiber at an assigned pump frequency;
• a partitioning unit that partitions the N optical signal channels into K wavelength regions and that provides an indication of a corresponding power variation for each wavelength region;
• a control unit that determines a corresponding pump power adjustment for each said Raman pump using a predetermined function, the predetermined function relating the corresponding power variation for each said wavelength region to the corresponding pump power adjustment for each said Raman pump,
• each said Raman pump adjusting a corresponding power output in accordance with the corresponding pump power adjustment.

A forward-pumped Raman fiber amplifier that supports N optical signal channels transported by an optical fiber facility, comprising:

• M Raman pumps, each Raman pump injecting optical power into the optical fiber facility at an assigned pump frequency;
• a partitioning unit that partitions the N optical signal channels into K wavelength regions and that provides an indication of a corresponding power variation for each wavelength region;
• a control unit for determining a corresponding pump power adjustment for each said Raman pump using a predetermined function, the predetermined function relating the corresponding power variation for each said wavelength region to the corresponding pump power adjustment for each said Raman pump, each said Raman pump adjusting a corresponding power output in accordance with the corresponding pump power adjustment, wherein the linear function comprises:
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• wherein k corresponds to a kth wavelength region, and wherein j corresponds to a jth Raman pump, ΔSL(k) corresponds to the corresponding power variation for the k wavelength region as linearly scaled, ΔPd(j) corresponds to the corresponding pump power adjustment of the jth Raman pump as logarithmically scaled, and TdL(j,k) corresponds to a linear coefficient relating the corresponding pump power adjustment of the jth Raman pump and the corresponding power variation of the kth wavelength region;
• and
• a fiber delay line, between a coupling point of the partitioning unit to the optical fiber facility and an injection point of the M Raman pumps to the optical fiber facility, for compensating for a delay time associated with processing by the control unit.