Patent ID: 7974002

Claim:
An optical communication system comprising: a plurality of optical transmitters operable to generate alone or collectively a plurality of wavelength signals at a bit rate of at least 9.5 gigabits per second and to communicate the plurality of wavelength signals over a multiple span communication link, wherein the plurality of wavelength signals comprise a bandwidth of at least sixty-five (65) nanometers separated into at least 160 optical channels, the plurality of optical transmitters adapted to generate the plurality of wavelength signals with each of the at least 160 optical channels separated from any adjacent optical channel within the at least 160 optical channels by a spacing of no more than 0.4 nanometers; and at least one discrete multi-stage Raman amplifier coupled to one or more spans of the communication link, the discrete multi-stage Raman amplifier comprising at least a first Raman amplification stage and a second Raman amplification stage, wherein the second Raman amplification stage is cascaded with the first Raman amplification stage, wherein each of the first Raman amplification stage and the cascaded second Raman amplification stage operate to amplify substantially all of the at least 160 optical channels of the bandwidth of at least sixty-five (65) nanometers of the plurality of wavelength signals, wherein the first Raman amplification stage provides a first gain profile that is approximately complementary to a second gain profile provided by the second Raman amplification stage such that the overall gain profile of the first and second Raman amplification stages is approximately flat.