Patent ID: 7280269

Claim:
A method for controlling a total gain of cascaded Raman fiber amplifiers in an optical fiber system that supports a plurality of optical signal channels, the method comprising: (a) determining an input signal power variation for at least one wavelength region, the plurality of optical signal channels being associated with the at least one wavelength region, wherein K denotes a number of wavelength regions; (b) determining a pump power adjustment for an adjustable optical pump using a dynamic control equation, the dynamic control equation relating the input signal power variation for the at least one wavelength region to the pump power adjustment for the adjustable optical pump, the dynamic control equation depending on a response time of the cascaded Raman fiber amplifiers and on a time instant; and (c) adjusting the adjustable optical pump in accordance with the pump power adjustment, wherein: (1) the cascaded Raman fiber amplifiers include a forward-pumped Raman fiber amplifier having at least one forward optical pump and a backward-pumped Raman fiber amplifier having at least one backward optical pump, (2) the adjustable optical pump being the at least one forward optical pump, and (3) the dynamic control equation including a first component and a second component, the first component corresponding to a first gain transient resulting from an essentially instantaneous co-propagating signal-to-signal and signal-to-pump Raman interaction, the second component corresponding to a second gain transient resulting from a counter-propagating signal-to-pump Raman interaction.