Polarization mode dispersion probability distribution for arbitrary distances

The probability distribution of the differential group delay (DGD) at any f iber length is determined by use of a physically reasonable model of the fi ber birefringence. We show that if the fiber correlation length is of the s ame order as or larger than the beat length, the DGD distribution approache s a Maxwellian in roughly 30 fiber correlation lengths, corresponding to a couple of kilometers in realistic cases. We also find that the probability distribution function of the polarization dispersion vector at the output o f the fiber depends on the angle between it and the local birefringence vec tor on the Poincare sphere, showing that the DGD remains correlated with th e orientation of the local birefringence axes over arbitrarily long distanc es. (C) 2001 Optical Society of America.