Research On Advanced Modulation Formats In High-Speed Long-Distance Optical Fiber Transmission System

High-speed optical fiber transmission system has gradually become the main technology of the main long-distance network transmission lines. Compared with the traditional cable transmission, it has a higher transmission rate and longer transmission distance to meet today's substantial increase in the amount of information. However, with the rise of transmission rate and transmission distance, the transmission quality loss that cause by the group velocity dispersion (GVD) impairment, nonlinear (cause by SPM and FWM) impairment and polarization mode dispersion (PMD) impairment and other issues will become more significant. Using a new modulation optical technology can effectively improve these problems, which have gradually become the key to high-speed long distance WDM system technology.In this dissertation we in turn introduce two forms of optical modulation and the devices related; research on the generator and receiver of amplitude modulation, phase modulation with different Mark-Space Ratio signals; then simulate the total rate of 80 Gbit/s Differential quadrature phase-shift keying (DQPSK) and Differential 8-ary phase-shift keying (D8PSK) transmission systems, analyze and compare their transmission performance by the GVD impairment, nonlinear impairment and PMD impairment. The results show that the D8PSK transmission has better performance in group velocity dispersion and polarization mode dispersion tolerance, and worse performance in nonlinear tolerance because of the higher power spectral density. Then we research on the phase-amplitude-shift keying modulation format, include the hexadecimal differential phase-amplitude-shift keying (HDPASK) signal's generator, receiver and its polarization division multiplexing (PDM) and wavelength division multiplexing (WDM) system; simulate the PDM-HDPASK transmission and make comprehensive analysis of transmission performance, including the external factors and modulator's parameters that effecting on the different Mark-Space Ratio signals and different tributaries (D8PSK tributary and ASK tributary). At last we research on the crosstalk of 4*320 Gbit/s WDM system. The results show that CSRZ-D8PSK and CSRZ-PDM-HDPASK has better performance.