Nonlinear polarization effects and mitigation in polarization-division-multiplexed coherent transmission systems

Using numerical simulations, the nonlinear transmission performance of polarization-division-multiplexed quadrature-phase-shift-keying （PDM-QPSK） coherent systems is studied. It is found that inter-channel cross-polarization modulation （XPolM） induced nonlinear polarization scattering can significantly degrade the transmission performance of PDM-QPSK coherent systems and change the perspective of dispersion management in optical coherent transmission systems. Some techniques to mitigate nonlinear polarization scattering in dispersion-managed PDM coherent transmission systems are discussed, including the use of time-interleaved return-to-zero （RZ） PDM formats, the use of periodic-group-delay PGD dispersion compensators, and the judicious addition of some polarization-mode-dispersion （PMD） in the transmission link. It is shown that if nonlinear polarization scattering can be well mitigated, a polarization multiplexed optical coherent transmission system with dispersion management could perform better than that without it.     

使用半导体光放大器的全光解复用器的性能分析

本文对使用半导体光放大器的Sagnac和Mach Zehnder全光解复用器进行了理论分析,在分析中综合考虑了控制脉冲宽度和半导体光放大器长度的影响。分析结果表明这种解复用器可获得的最小开关窗口由控制脉冲宽度和半导体光放大器长度决定,此外由分析可知,不但这种解复用器的开关速率,而且其被解出的分支信号的速率都不受半导体光放大器张弛时间的限制。