Dynamics and quantum fluctuations of light in nonstationary operation modes of a Raman fibre amplifier

We report the results of numerical simulation of the radiation dynamics in a Raman fibre amplifier taking into account quantum fluctuations of the pump fields and Stokes waves. The simulation relies on an approach based on solutions of the transport equations for complex amplitudes and on the 'backward' propagation method for operators describing quantum fluctuations. It is shown that there exists an optimal Raman amplifier length corresponding to the minimum level of fluctuations of the amplified Stokes pulse.