A Novel Method for Multi-Pumped Fibre Raman Amplifier Gain Adjustment

A novel method for gain adjustment of multi-pumped fibre Raman amplifiers is proposed and numerically demonstrated. The method uses the areas under the curves of the pump power evolution along the gain fibre and the Newton--Raphson method to find an appropriate power combination of the pumps to realize the desired gain profile. Compared with the previously proposed methods, our method has two advantages: first, it can maintain the gain profile while changing the gain magnitude to the desired value; second, it is independent of the actual pumping scheme of the amplifier, i.e. it can be used for fibre Raman amplifiers with all kinds of pumping schemes including co-, counter-, or bi-directional pumping. Numerical simulations are provided to verify the proposed method and to demonstrate its effectiveness.