Patent ID: 7280271

Claim:
A cascaded Raman amplifier combination that is responsive to an optical signal having a plurality of optical signal channels, comprising: a first Raman fiber amplifier having an adjustable optical pump; a second Raman fiber amplifier; a measurement unit configured to determine an input signal power variation for a 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; a control unit configured to determine a pump power adjustment for the adjustable 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 amplifier combination and on a time instant, and wherein the adjustable optical pump is configured to adjust a pump power output in accordance with the pump power adjustment, wherein: (1) the first Raman fiber amplifier being a forward-pumped Raman fiber amplifier having at least one forward optical pump and the second Raman fiber amplifier being 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.