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高速率、大容量的密集波分复用系统是光纤通信系统的最终发展方向 ,单信道速率达到 4 0Gbit/s时 ,光纤的非线性效应、偏振模色散现象对系统的影响更加突出。在综合考虑群速度色散、自相位调制、交叉相位调制、四波混合、偏振模色散等因素的基础上 ,推导了密集波分复用系统中任意信道的耦合非线性薛定谔方程组。利用扩展的分步傅里叶方法对该方程进行了数值计算 ,通过对 8× 4 0Gbit/s密集波分复用系统的仿真 ,分别研究了非线性效应和偏振模色散对密集波分复用系统的影响。发现由于交叉相位调制和四波混合作用 ,多波长的密集波分复用系统比单波系统受非线性效应影响严重 ;系统受偏振模色散与非线性效应的影响程度与输入信号功率有关 ,在入射光单信道平均功率较低 0 .1mW时 ,偏振模色散是影响系统性能的主要因素 ;当入射光单信道平均功率较高1mW时 ,系统受非线性效应影响严重。而偏振模色散在使信号脉冲展宽的同时 ,类似于非零色散位移光纤中的微小色散 ,对非线性效应又有一定的抑制作用。
Dense wavelength division multiplexing system with high speed and large capacity is the ultimate development direction of optical fiber communication system. When the single channel rate reaches 40 Gbit / s, the nonlinear effect and polarization mode dispersion of optical fiber have a more prominent impact on the system. Based on the consideration of group velocity dispersion, self phase modulation, cross phase modulation, four-wave mixing, and polarization mode dispersion, the coupled nonlinear Schrödinger equations for arbitrary channels in Dense Wavelength Division Multiplexing systems are derived. The extended step-by-step Fourier method was used to numerically calculate the equation. The simulation of the 8 × 40 Gbit / s dense wavelength division multiplexing system was carried out to study the effects of nonlinear effects and polarization mode dispersion on the Dense Wavelength Division Multiplexing System impact. It is found that due to the cross-phase modulation and the four-wave mixing, the multi-wavelength Dense Wavelength Division Multiplexing system is more seriously affected by the non-linear effect than the single-wave system. The influence of polarization mode dispersion and nonlinear effect on the system power is related to the input signal power. Polarization mode dispersion is the main factor affecting system performance when the average power of incident single channel is lower than 0.1 mW. When the average power of incident single channel is higher than 1 mW, the system is seriously affected by the nonlinear effect. The polarization mode dispersion in the signal pulse broadening at the same time, similar to the non-zero dispersion in the dispersion of small dispersion fiber, the nonlinear effect has a certain inhibitory effect.