Optical transmission link including raman amplifier

An optical communications system for transmitting optical signals on a fiber link, said system comprising:

• a plurality of input channels, each input channel including a laser generating an optical signal and a polarization controller for controlling the polarization of the optical signal;
• a multiplexer responsive to the optical signals in the plurality of input channels, said muliplexer multiplexing the plurality of optical signals onto a single output;
• a single span fiber coupled to the output of the multiplexer and receiving the plurality of optical signals therefrom;
• a pump source for introducing depolarized pump light into the fiber, said pump source including at least one optical source generating a polarized pump signal, an optical splitter that splits the pump signal from the optical source into a first pump portion and a second pump portion, a delay device that delays the first pump portion relative to the second pump portion, and a beam combiner that receives the delayed first pump portion and the second pump portion and combines the pump portions to form the pump light, wherein the pump light includes optical energy in at least two orthogonal polarization states so that the pump light is depolarized;
• a demultiplexer coupled to and receiving the plurality of optical signals on the fiber, said demuliplexer demultiplexing the plurality of optical signals into a plurality of outputs;
• and
• a plurality of output channels coupled to the outputs of the demultiplexer, each output channel including a receiver.