Small signal Raman amplification of optically carried microwave signals

In this paper, we show that stimulated Raman amplification (SRA) in silica fiber can be used for low noise amplification of such small optically carried microwave signals. Indeed, at low signal amplification the gain and the total spontaneous noise power are both proportional to the transition linewidth. Due to the extremely large linewidth of silica, the spectral density of amplified spontaneous emission (ASE) must be very low in fiber SRA amplifiers.