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.

仿真并分析了基于半导体光放大器全光偏振调制的双信道光传输系统模型.该系统分别利用两级半导体光放大器的交叉偏振调制效应(XPolM)，将两路独立的强度调制的抽运光变换到一路探测光的两个正交的偏振态上，实现双通道偏振复用的全光数据传输.首先对单个半导体光放大器的动力学过程进行了理论分析，数值计算了具有不同抽运光功率的半导体光放大器对探测光偏振态的影响，进而对双半导体光放大器偏振复用系统的调制/解调原理进行了分析，模拟仿真了双半导体光放大器的双通路偏振复用的调制及解调过程，仿真结果与实验结果相符.

在半导体光放大器中，采用由张应变引起的自身双折射理论模型对交叉偏振调制型全光波长转换器的波长转换特性进行了数值研究，并对数值结果与相关实验进行了对比。结果表明：通过调节系统参量，可以实现同相或反相波长转换；同相和反相波长转换时输出的信号啁啾、消光比和眼图具有不同特性；随着数据传输速率的增加，输出信号的眼图张开度减小，啁啾变大。

半导体光放大器(SOA)中非线性系数约为普通光纤的109倍，为光子晶体光纤的107倍。有4种光-光互作用，即交叉增益调制、交叉相位调制、交叉偏振调制和四波混频，可以灵活地组成各种光信号处理器件，如波长变换器、全光触发器、全光逻辑、全光时钟恢复、全光缓存器，正成为整个光信号处理的基础。介绍了这些技术的同时，分析当前应用的制约因素，指出半导体光放大器集成是下一步发展的必然趋势。

半导体光放大器(SOA)中非线性系数约为普通光纤的109倍,为光子晶体光纤的107倍。有4种光-光互作用,即交叉增益调制、交叉相位调制、交叉偏振调制和四波混频,可以灵活地组成各种光信号处理器件,如波长变换器、全光触发器、全光逻辑、全光时钟恢复、全光缓存器,正成为整个光信号处理的基础。介绍了这些技术的同时,分析当前应用的制约因素,指出半导体光放大器集成是下一步发展的必然趋势。

We have studied a function-lock strategy for all-optical logic gate (AOLG) utilizing the cross-polarization modulation (CPM) effect in a semiconductor optical amplifier (SOA). By monitoring the power of logic light, the strategy realized controllable methods to capture OR and NOR functions and switch between them. The strategy has been successfully applied in experiment with 10-Gb/s not-return-to-zero (NRZ) signals, which has a high success-rate above 95% and ensures the high extinction ratio of result light above 11.4 dB. Every step in the strategy has definite numeric evaluation, which provides the potential of automatic implementation.

利用琼斯矩阵，对基于半导体光放大器中的交叉偏振调制效应实现全光波长变换进行了理论分析．结果表明，利用这种机制可以实现同相与反相波长变换．在实验上同时实现了10 Gb／s归零信号的正相与反相波长变换，输出消光比分别达到了6．9 dB和8．1 dB．

为了改善基于半导体光放大器(SOA)中交叉偏振调制效应(CPM)的波长转换器的转换信号码型效应,对交叉偏振调制半导体光放大器波长转换器的工作原理进行了分析;通过讨论交叉偏振调制半导体光放大器波长转换脉冲的上升沿和下降沿的频率啁啾,结合滤波器的透过谱特性,提出了一种利用滤波器的波长正斜率边和波长负斜率边分别对正相转换信号和反相转换信号进行码型优化的方案,并进行了实验验证。在信号码率为10 Gb/s的交叉偏振调制半导体光放大器波长转换实验中,采用光带宽为0.3 nm的JDS滤波器优化转换信号的波形,基本消除了转换信号中长“1”码和长“0”码的码型效应,并将正相转换信号和反相转换信号的功率代价分别改善了3 dB以上。