Shared forward pumping in optical communications network

A pump assembly for an optical amplifier, comprising:

• a first plurality of pump radiation sources, each pump radiation source producing radiation at a respective one of a first number of pump wavelengths, at least some of the first number of pump wavelengths having different wavelengths;
• a first coupler, optically coupled to each of the plurality of pump radiation sources, which receives the radiation at each of the first number of pump wavelengths from the first plurality of pump radiation sources and outputs the radiation at each of the first number of pump wavelengths to each one of a second number of outputs;
• a first plurality of pump signal combiners, each pump signal combiner optically coupled to a respective one of the second number of outputs of the first coupler and receiving the radiation at each of the first number of pump wavelengths output from the first coupler, each pump signal combiner placing the radiation at each of the first number of pump wavelengths output from the first coupler in co-propagation with a respective one of a plurality of data signals propagating on a respective one of a plurality of optical fibers, to provide stimulated Raman scattering amplification in the plurality of optical fibers;
• a second coupler having outputs corresponding to the second number, which receives radiation at each of a third number of pump wavelengths from a second plurality of pump radiation sources and outputs the radiation at each of the third number of pump wavelengths to each one of the second number of outputs of the second coupler, the range of pump wavelengths for the third number of pump wavelengths being substantially greater than the range of pump wavelengths for the first number of pump wavelengths;
• and
• a second plurality of pump signal combiners, each pump signal combiner optically coupled to a respective one of the second number of outputs of the second coupler and receiving the radiation at each of the third number of pump wavelengths output from the second coupler, each pump signal combiner placing the radiation at each of the third number of pump wavelengths output from the second coupler in counter-propagation with a respective one of the plurality of data signals propagating on a respective one of the plurality of optical fibers, to provide stimulated Raman scattering amplification in the plurality of optical fibers.