
as the PMD (or DGD) coefficient with typical units of picosecond per kilometer
(for very short fibers) or picosecond=km
1=2
for long fibers. Because any polar-
ized lightsource consists of a range of wavelengths, after propagation through
a length of fiber a range of polarizations will be present, one for each wave-
length. In this way, a source will depolarize because of its own finite line
width (the PMD required for depolarization is roughly equal to the source
coherence time).
2.8.3 Modeling and Simulation
The evolution of the lightwave polarization is most conveniently studied in
terms of Stokes vectors in Poincare
´
space [36]. The three-dimensional ...