单模光纤偏振模色散(PMD)的理论

Theories of Polarization Mode Dispersion (PMD) in Single Mode Fiber

系统地研究了有关偏振模色散（ＰＭＤ）的一些理论，包括ＰＭＤ的起因、估算、模式耦合、标称值的确定等。指出了双折射是引起ＰＭＤ的首要原因，说明了光纤材料的形状、应力、弯曲、扭转及电磁场等因素都能导致双折射。而模式耦合则是影响ＰＭＤ的一系列特性（例如ＰＭＤ与长度的依赖关系等）的重要原因。

This paper formulates some theories on the polarization mode dipersion (PMD) involving origination 、estimation、mode coupling and standardization of PMD.We point out the birefringence is the chief cause of PMD while the birefringence can be caused by the anisotrpic shape、 stress、bending、twisting and eletromagnetic field of the fiber materials.Furthermore,mode coupling can signally affect some performance of PMD,such as the mutual dependence between PMD and link length.The suggested methods for determining PMD standard value are presented as well.