Abstract

Use of novel incoherent pump source to dual-stage fiber Raman amplifiers (FRA's)✹dispersion compensated fiber Raman amplifier (DCRA) is investigated and the performance is compared to results with the conventional coherent pumping for the first time. To achieve accurate modeling, a theoretical model of FRA's, which includes effects of multiple-path interference (MPI), anti-Stokes, and Rayleigh scattering, is used. Modeling of the incoherent pump is also given theoretically. This model is tested to be accurate. Investigations are based on above models of DCRA with one and two incoherent pumps. By comparing the performances of DCRA with coherent pumps, we concluded that better gain and noise performance can be achieved using less incoherent pumps than coherent pumps. Also, gain flatness and OSNR flatness of the dual-stage fiber Raman amplifiers are investigated separately and simultaneously, using one and two incoherent pumps. Optimum parameters of the incoherent pump such as center wavelength, FWHM (full width at half maximum) and pump power are found for signal bandwidths up to 100 nm. It is shown that in this combined configuration, there is a trade-off in obtaining the flatness of gain and OSNR. But with a suitable pumping scheme, both gain and OSNR flatness can be achieved simultaneously.