Noise Gain Features of Fiber Raman Amplifier

Abstract

The formation dynamics of the optical noise in a silica single mode fiber (SMF) as function of the pump power variation in the counter pumped fiber Raman amplifier (FRA) is experimentally studied. The ratio between the power of amplified spontaneous emission and the power of incoherent optical noise is quantitatively determined by detailed analysis of experimental data in the pump powers range of 100–300 mW within the full band of Stokes frequencies, including FRA working wavelengths over the C + L transparency windows. It is found out the maximum of Raman gain coefficient for optical noise does not exceed ~60% of corresponding peak at the gain profile maximum of coherent signal. It is shown that the real FRA noise figure may be considerably less than 3 dB over a wide wavelength range (100 nm) at a pump power of several hundreds of mW.

Spectroscopic Features of Raman Gain Profiles in Single-Mode Fibers Based on Silica Glass

“…As the pump power increases, the exponential growth in the amplified noise as compared with a non-coherent Stokes noise background independent of the pumping is observed [30]. By the careful analysis of a deformation of the noise spectra under the pumping influence, we were able to separate the coherent amplified Raman noise from the background of the spontaneous Stokes noise, which is discussed in [31], [32] in more details.…”