Patent ID: 7197245

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 spanning at least 400 kilometers without optical regenerators, wherein the plurality of wavelength signals comprise a bandwidth of at least sixty-five (65) nanometers separated into at least 160 optical channels, and wherein at least a majority of the transmitters implement a forward error correction (FEC) coding technique and communicate to the communication link FEC encoded wavelength signals, and wherein the FEC encoded wavelength signals comprise a bit error rate of 10−09 or better after FEC decoding at a receiver coupled to the communication link; at least five (5) optical add/drop multiplexers (OADMs), each coupled to one or more spans of the multiple span communication link; a plurality of discrete amplifiers each coupled to one or more spans of the communication link, at least one of the plurality of discrete amplifiers comprising a discrete multi-stage Raman amplifier, 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, and wherein each of the at least 160 optical channels amplified by the discrete multi-stage Raman amplifier is separated from any adjacent optical channel within the at least 160 optical channels by a spacing of no more than 0.4 nanometers; and a plurality of distributed Raman amplification stages each coupled to at least one of the plurality of discrete amplifiers.