Fast dynamic gain control in an optical fiber amplifier

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 Raman fiber amplifier having a feed-forward control configuration, 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 with the feed-forward control configuration, the predetermined function relating the corresponding power variation for each said wavelength region to the corresponding power adjustment for each said Raman pump;
• and
• (d) adjusting each said Raman pup in accordance with the corresponding power adjustment.

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 kth wavelength region, wherein j corresponds to a jth Raman pump, ΔSL(k) corresponds to the corresponding power variation for the kth wavelength region as linearly scaled, ΔPL(j) corresponds to the corresponding pump power adjustment of the jth Raman pump as linearly scaled, and TLL(j,k) corresponds to a linear coefficient relating the corresponding pump power adjustment of the jth Raman pump and the corresponding power variation for the kth 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 kth wavelength region;
• and
• (f) determining the linear coefficient TLL(j,k) by calculating ΔPL(j)/ΔSL(k).

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
• d
• ⁡
• (
• j
• )
• ≈
• ∑
• k
• =
• 1
• K
• ⁢
• T
• d
• ⁢
• ⁢
• L
• ⁡
• (
• j
• ,
• k
• )
• ⁢
• Δ
• ⁢
• ⁢
• S
• L
• ⁡
• (
• k
• )
• ,
• wherein k corresponds to a kth wavelength region, wherein j corresponds to a jth Raman pump, ΔSL(k) corresponds to the corresponding power variation for the kth 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 for the kth 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 kth wavelength region;
• and
• (f) determining the linear coefficient TdL(j,k) by calculating ΔPd(j)/ΔSL(k).

A method for controlling a gain of a forward-pumped Raman fiber amplifier having M Raman pumps in an optical fiber system that supports N optical signal channels, the forward-pumped Raman fiber amplifier having a feed-forward control configuration 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) inducing an induced time delay to compensate for an associated time delay associated with a gain control loop;
• (d) determining a corresponding pump power adjustment for each Raman pump using a linear function with the feed-forward control configuration, wherein the linear function relates the corresponding power variation for each said wavelength region to the corresponding power adjustment for each said Raman pump, and wherein the linear function comprises:
• Δ
• ⁢
• ⁢
• P
• d
• ⁡
• (
• j
• )
• ≈
• ∑
• k
• =
• 1
• K
• ⁢
• T
• dL
• ⁡
• (
• j
• ,
• k
• )
• ⁢
• Δ
• ⁢
• ⁢
• S
• L
• ⁡
• (
• k
• )
• ,
• wherein k corresponds to a kth wavelength region, wherein j corresponds to a jth Raman pump, ΔSL(k) corresponds to the corresponding power variation for the kth 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
• (e) adjusting each said Raman pump in accordance with the corresponding power adjustment.