||With the essence of robustness toward fiber nonlinearity owing to the increasingly required high-speed data rate from the country to country or country to the state, many useful methods are proposed upon the long-haul optical fiber transmission, such as modulation format, dispersion map and repeater spacing, etc. Return-to-zero differential phase shift keying (RZ-DPSK) format was chosen in this master thesis because of its high tolerance toward nonlinear effect in the wavelength-division multiplexing (WDM) system transmission.|
It has been realized that the system performance is wavelength-dependent by the combination of the WDM technology and the RZ-DPSK system with the commonly used block-type dispersion map, especially for the significant performance difference between including or excluding the self-phase-modulation (SPM) effect. Therefore, it is quite significant to investigate the unwanted fiber nonlinearity. In this master thesis, the influence relating to the cross-phase modulation (XPM) effect and the SPM effect with the conventional dispersion map after long distance transmission is the mainly concerned issue to be discussed.
In this master thesis, both experiment and theoretical simulation are investigated. On the theoretical simulation part, the Q-factor of the system zero dispersion wavelength at 1543.8nm, 1550nm, 1556.2nm were degraded and their value were less than 10dB. The Q-factor was around 1.5dB less than the averaged value. However, the performance of the long-haul RZ-DPSK system based on the block-type dispersion map shows no significant performance by shifting the system zero dispersion wavelength out of the WDM signal wavelength band. On the experimental part, the impact of the XPM effect and the SPM effect on the long-haul optical fiber communication system is investigated quantitatively. For the XPM experiment, the system performance was just only 0.1 dB difference after 6000km transmission. On the contrary, for the SPM experiment, the Q-factor between best and worst performance was up to 1.3dB difference. At last, the experiment and the simulation support each other successfully in this master thesis.