Variation of system performance in a 107 km dispersion managed recirculating loop due to polarization effects

Summary form only given. Polarization effects can have a severe impact on the performance of long-haul multigigabit light wave system using erbium-doped fiber amplifiers (EDFAs). Recirculating loops are commonly used as experimental models for studying long-haul transmission systems, making it important to understand the polarization effects inside these loops. Our prior study shows, experimentally and theoretically, that in short loops both the signal and noise become highly polarized as a function of propagation distance when the PDL (polarization dependent loss) is large. in the present research we lowered the PDL of our loop to a point where the PDG (polarization dependent gain) becomes important. We then measured the Q factor distribution of our loop at 5000 km and compared the measured result with theoretical calculation using a reduced model. We were able to show by measurement and subsequent analysis that even after randomizing the polarization state in the loop the Q factor distribution was far from what is expected for a randomized straight-fine system. In addition we are able to show simplified methods for realizing in recirculating loops a more randomized Q distribution appropriate for emulating straightline experiments.