光纤通信系统的偏振模色散(PMD)是限制系统传输容量和距离的关键因素。系统输出信号的偏振度(DOP)反映了系统的偏振模色散。利用光纤通信系统的Jones矩阵模型,在理论上得到了系统的输出光脉冲Stokes矢量的表达式。在此基础上分析和计算了系统的输出脉冲的偏振度特性。结果表明,系统的输出信号的偏振度随入射脉冲偏振态的变化而变化,当入射脉冲偏振态与系统的主偏振态一致时,系统的输出信号的偏振度达到极大;同时,随着系统的偏振模色散幅度的增大而变小。系统的输出信号的偏振度还随着信号原始啁啾系数绝对值的增大而减小,但与啁啾系数的符号无关。

The polarization mode dispersion (PMD) of the optical fiber transmission system has been the main factor to limit the transmission capacity and distance of the system. The degree of polarization (DOP) of optical signals is related to the PMD of the system. The expression of the output pulse Stokes vector is derived based on Jones matrix model proposed by A. Orlandini. The basic properties of degree of polarization of optical pulse have been investigated. It is shown that the degree of polarization of optical signals changes with polarization state of the input, and reaches its maximum at the position of the principal state of polarization; it decreases with the increase of the PMD magnitude; And it decreases also with the increase of absolute value of the initial pulse chirp coefficient, but has no relation with the sign of chirping coefficient.