Stimulated Raman scattering for variable gain amplification of small optically carried microwave signals

Stimulated Raman amplification of optically carried microwave signals in optical fibers is experimentally investigated. In the backward configuration which is shown to be less noisy than the forward one, net amplification factors larger than 20 dB are demonstrated in the low signal regime with better relative intensity noise (RIN) values than using erbium-doped-fiber amplifiers. Due to the RIN flatness with respect to the gain of the stimulated Raman amplifier high quality variable gain amplification of optically carried microwave signals could be implemented using optimized Raman amplifiers.