Study of the two-frequency moment generating function of the PMD vector

We study the properties of the polarization-mode dispersion (PMD) vector as a stochastic process in frequency. An equation for the joint-moment-generating function of PMD at two offset optical frequencies is derived and used to obtain analytical expressions for the conditional first and second moments of PMD. We find Mat the rate at which the PMD vector decorrelates in frequency does not depend on whether its modulus is significantly different from its average value.