An approach to analyze quantitavily pump-pump interaction in Raman amplifiers

We report a simple and straightforward approach to analyze quantitatively pump-pump interaction contribution to wide-band Raman amplifier gain profile. The approach is based in the numerical solution of Raman amplification equations. The on-off gain difference in the presence and absence of pump-pump interaction depicts a degree of odd symmetry in gain profile around the center of the amplification band. Additionally, the approach evidences a pump power threshold level where pump-pump interaction plays a relevant role in gain profile. The approach is demonstrated for modern low loss fibers under three and two pump excitation.