Dynamical equation for polarization dispersion.

Polarization dispersion in single-mode fiber that contains arbitrary birefringence is described through a vector differential equation. Monte-Carlo simulations using this equation show good agreement with experimental measurements in a randomly birefringent fiber and with a previously reported analytic expression for the length dependence of the dispersion. We also correct an error made in earlier research and show that the probability density function for the magnitude of the dispersion at long lengths is Maxwellian rather than Gaussian as previously reported.