Abstract: A Raman pump unit for connection to a main optical path includes a signal generator for generating a plurality of at least partially complementary dither signals, a plurality of modulators connected to said signal generator capable of receiving pump driver signals and modulating these in accordance with the dither signals and a plurality of pumps connected to the modulators for receiving producing optical pump signals from the modulated pump driver signals. The unit also includes an optical coupler connected to the plurality of pumps for introducing a combination of the optical pump signals into the main optical path. The use of pump dithering increases the spectral width of the optical pump signals being injected into the main optical path, which helps to fight the deleterious effects of SBS. Meanwhile, pump noise transfer to the main optical signal is mitigated because the signal gain is the combination of two at least partially complementary pump dither signals.