WDM System Characteristics Of Polarization Mode Dispersion

Dense Wavelength Division Multiplexing (DWDM) is a new communication technology that is rapidly progressing during recent years. In DWDM, the nonlinear effects such as self-phase modulation(SPM), cross-phase modulation(XPM) become important. With the transmission rate increasing, polarization-mode dispersion (PMD) causes more and more severe influence on the performance of system. It is proved that hyperbolic-secant pulses (solitons) have inherent ability to suppress PMD, this adaptive ability is due to the balance between nonlinear XPM effect and PMD effect.It is studied on the influence of polarization-mode dispersion on WDM system in this dissertation. The achievements are as follows:1. The general nonlinear propagation equations of four-lightwaves in birefringent fibers are deduced. The characteristics of polarization mode dispersion in 4 + 10Gb/sDWDM system in dispersion-flattened fibers is studied. Our results show that PMD exerts a detrimental influence on 4 X lOGb/sDWDM system in limiting transmission rate and the channel numbers.2. Because lightwave systems commonly use fibers with randomly varying birefringence, it is important to study how optical pulses are affected by random birefringence changes. We introduce a model of random birefringent single mode fibers, and the general nonlinear propagation equations of dual-lightwaves in random birefringent fibers are deduced. The characteristics of polarization mode dispersion in 2 +10Gb/sWDM system is studied. It is found that PMD in WDM system can be effectively suppressed by the synchronous modulation technique. Our results show that PMD induces pulse broadening randomly in high bit-rate optical fiber communications; the synchronous amplitude modulation control may correct directly any position change of timing jitter and soliton interaction, so the transmission distance and pulse quality will increase further.