Pulse distortion in single-mode fiber due to bending-induced polarization mode dispersion and polarization dependent loss

With the increasing bit rate in optical fiber communication, both polarization mode dispersion (PMD) and polarization dependent loss (PDL) are recognized as the most important limiting factors. Mechanical bending encountered in the field affects PMD and PDL and causes additional input pulse distortion, resulting in system degradation. Gisin and Huttner (1997) reported the combined effects of PMD and PDL in optical fibers. However, effects on pulse distortion of the bending-induced PMD and PDL in single-mode fibers has not yet been reported. In this paper, we calculate the pulse width difference between input and output pulses as a function of the bending radius. To visualize output pulse distortion, a normalized output pulse shape is also given at a certain fixed bending radius. For calculations, we initially assume that the long fiber cable is modeled as two concatenated uniform fibers with both intrinsic PMD (1st order) and PDL. Based on this model, we add a virtual fiber section between two sections in order to consider a bending-induced PMD and PDL.