Modelling and simulation of the combined effects of the fiber nonlinear phenomena on the system performance of passive optical access networks

Wavelength Division Multiplexing Passive Optical Network (WDM-PON) is playing an important role on modern optical network communication systems and becomes a good choice for long-haul networks since it provides flexibility in design and enhances the transmission capacity. Currently, Gigabit Passive Optical Network (GPON) structures promise important features for access networks. System specifications such as input power per channel, channel spacing values, channel numbers and total transmission length have important roles in overall system performance as well as the nonlinear effects in optical fibers limiting the system performance. Among all nonlinear phenomena in the optical fiber, stimulated Raman scattering (SRS) and four wave mixing (FWM) are known to have the major impact on performance limitations in optical fiber systems. In this thesis, using the variations on signal-to-crosstalk ratio (SXR), i.e. the ratio of the modified signal power due to SRS to the FWM crosstalk power, comparative analysis of the combined impact of SRS and FWM with the single impact of FWM on the ultra-dense/dense wavelength division multiplexed gigabit passive optical network (UDWDM/DWDM-GPON) systems has been accomplished. Furthermore, variation of the amplification factor of the Stokes wave, i.e. the Raman gain (GR), with system parameters has been also analyzed. Simulation results show that SRS compensates negative impacts of FWM and the significance of compensation enhances with increasing channel numbers and channel spacing values. In addition, it has been observed that the Raman gain exhibits an approximately linear variation with channel input powers in the range of 0.1-5 mW and it increases with increasing fiber lengths, channel spacing values and channel numbers. Simulation results emphasize the significant difference between the combined impact of SRS and FWM and the single impact of FWM on the system performance and give important clues for current/future UDWDW/DWDM-GPON implementations.