Effect of Raman Gain on Broadband Fiber Optical Parametric Amplifiers and Wavelength Converters

Recently we have shown theoretically that two-pump fiber optical parametric amplifiers (OPA’s) can exhibit highly uniform broadband gain spectra [1]: for example one can obtain 20 dB of gain over a 45 nm bandwidth, with uniformity of 0.2 dB. These calculations, however, did not include the effect of stimulated Raman scattering (SRS). Here we study the influence of SRS on the uniformity of the OPA gain spectrum, by starting from four-wave mixing (FWM) equations including SRS gain contributions. We show that in general SRS modifies the OPA gain spectrum, but that under realistic conditions the uniformity can remain quite good.