Abstract

Due to manufacturing inhomogeneities and external stresses in fibers, degeneracy between the two modes of propagation vanishes and leads to an unwanted birefringence which varies along the fiber.¹ Polarization-Mode Dispersion (PMD) applies to a modulated signal and accounts for the frequency dependence of the polarization state of its spectral components. In a first-order approach in frequency, a modulated signal is depolarized unless its input state of polarization (ISOP) is along one of two preferential vectors on the Poincaré sphere: the Principal States of Polarization (PSP). Because of different group velocities along the two PSP, the two components of an input along the directions of PSP are shifted in time by the Differential Group Delay (DGD) after propagating. Thus PMD brings about signal distortions which cause system impairments in a statistical way. PMD stochastic nature lies in the time dependence of the local birefringence. Furthermore, due to frequency dependence of birefringence, one must overtake this first-order frame of work in order to be more realistic and take into account the DGD and PSP variations with frequency respectively called Polarization-dependent Chromatic Dispersion (PCD) and depolarization (2k).²

© 2002 Optical Society of America