Raman amplification is a wide-band phenomenon having a highly irregular gain profile over wavelength. The highest Raman gain is observed for a frequency differential range (range of difference between pump signal and data signal nominal frequencies) of 8 to 12 THz. Outside this range, the gain profile exhibits a sharp decline. Therefore, if the number of pumps, their wavelengths, and the power values are chosen carefully, we can achieve the desired gain shape for the input DWDM channels.
Figure below shows numerical values of eight pump-power and wavelengths selected after several simulation pre-runs and the Raman amplified output.