光纤通信系统中基于光学相位共轭和预啁啾的色散及非线性补偿研究

采用光学相位共轭补偿光纤通信系统的色散及非线性必须满足一个前提条件，即相位共轭器两边线路上的色散和非线性分布(或传输功率分布)必须严格对称，这在现有的一般传输线路（标准单模光纤加集总掺铒光纤放大器）难以实现。提出了预啁啾结合中距相位共轭的补偿方案，并进行了数值计算。结果表明，通过在发送端对输入脉冲进行预啁啾展宽，可有效地减轻非线性效应与色散的相互作用，获得理想的补偿效果；对于皮秒超短光脉冲传输，脉冲内拉曼散射相对于三阶色散对补偿结果的影响很小，因此，频域相位共轭相对于时域相位共轭具有更好的综合补偿性能。该方案简单易行，无需对已敷设好的线路作较大改动。

Dispersion and Nonlinearity Compensation in Optical Fiber Communication Systems by Optical Phase Conjugation Incorporated Pulse Prechirp

One of the major limitations of optical phase conjugation (OPC) for dispersion and nonlinearity compensation in optical fiber communication systems is that the power profile along the communication links should be symmetrical with respect to the optical phase conjugator. However, such a power profile is difficult to be realized in practical systems in which the communication link is composed of uniform fibers and periodic amplification using erbium-doped fiber amplifiers. It is numerically demonstrated that the difficulty can be overcome if the OPC is used in combination with pulse prechirp. Pulse prechirp can greatly reduce the interplay between the dispersion and nonlinearities and improve the communication performance. It is also shown that the effect of intra-pulse Raman scattering on the communication scheme is much smaller than that of third-order dispersion even for picosecond ultrashort pulses. Thus, more effective compensation can be achieved if spectral phase conjugation is used, instead of temporal phase conjugation for the scheme. The scheme is simple and effective, and it eliminates the need for special design or significant modification of the communication link.