The properties of amplified spontaneous emission noise in saturated fiber Raman amplifiers operating with CW signals

This paper describes the properties of amplified spontaneous emission (ASE) noise in forward and backward pumped saturated Raman amplifiers operating with CW signals. Analytical and numerical calculations confirmed by experiments demonstrate that ASE noise propagating in the pump direction (the direction of increasing gain) is compressed faster than the gain. This is in clear contrast to saturated erbium doped fiber and semiconductor amplifiers where the gain is compressed faster than the noise under all circumstances. (C) 2004 Elsevier B.V. All rights reserved.