Abstract: An optical radiation adapted for use in Raman amplification in a given band, is generated from a low power optical radiation with a respective bandwidth, generated by a plurality of master oscillators, such as low-power laser diodes whose output radiation is multiplexed by a multiplexer. A Raman amplification medium is provided, such as a length of optical fiber, and an additional optical radiation adapted for use in Raman amplification in said Raman amplification medium is generated. Both the low-power optical radiation and the additional optical radiation are injected into the medium so to produce, by the Raman effect induced in the medium, the output optical radiation.