Performance of lumped fiber Raman amplifiers using highly nonlinear fibers or nonlinear photonic crystal fibers

Abstract

Lumped fiber Raman amplifiers (LFRAs) using highly nonlinear fiber (HNLF) are investigated and compared to using dispersion compensating fiber (DCF). It is shown that both the signal and amplified spontaneous emission induced multiple-path interferences are reduced in HNLF, thus for a same Raman gain a better noise performance of LFRAs using HNLF can be achieved compared to using DCF. It is found that noise figure over the C+L band can be improved by ~6.7 dB for a Raman gain of ~15 dB for a LFRA using HNLF compared to DCF with counter-pumping.