Multiple raman pump assisted fiber optical parametric amplifiers

We studied the use of multiple Raman pumps to assist fiber optical parametric amplifiers (FOPAs). We derived a theoretical model to describe the performance of multiple Raman pump assisted FOPAs. We demonstrated that the over 40 nm flat gain bandwidth provided by the multiple Raman pumps can be used to support the parametric gain bandwidth of Raman-assisted FOPAs (RA-FOPAs). We also found that if indirect Raman gain contribution dominates, by using dispersion-flattened highly nonlinear fiber with small dispersion slope and polarization-mode dispersion effect, broadband FOPA with broad parametric pump wavelength tuning range can be obtained by using multiple Raman pump assistance. On the other hand, if direct Raman gain contribution dominates, the parameters of the multiple Raman pumps have to be chosen carefully to ensure that the Raman gain bandwidth matches the parametric gain bandwidth in order to achieve a flat gain with broad gain bandwidth in the RA-FOPAs.