Polarization Control Methods for Mitigating Four-Wave Mixing Effect in NG-EPON Networks

In order to meet the growing traffic demands, the formulation of the NG-EPON protocol is under heated discussion. Therefore, for the wavelength allocation scheme of NG-EPON, adopting O-band wavelengths is considered as the potentially feasible solution. While the low dispersion property of O-band would induce four-wave mixing (FWM) to NG-EPON networks. In this paper, polarization control methods are used to mitigate the FWM effect in NG-EPON networks, including orthogonal linear polarization, circular polarization and left to right circular polarization alternation methods. For the 4-channel NG-EPON networks, the FWM-induced sensitivity penalty is achieved as 0.3 dB by using the orthogonal linear polarization method, compared with the FWM-induced sensitivity penalty of 4.1 dB, which is the worst-case scenario. By adopting the circular polarization method, the FWM-induced sensitivity penalty is measured as 0.2 dB, which is 3.9 dB better than that of the worst-case scenario. By employing the left to right circular polarization alternation method, the FWM-induced sensitivity penalty is 0.2 dB, compared with the worst-case scenario, whose sensitivity penalty is 4.1 dB induced by the FWM. In addition, for the 8-channel NG-EPON networks, the FWM-induced sensitivity penalty is decreased to 0.4 dB for minimum, compared with the worst-case scenario, whose sensitivity penalty is unpredictable.