Statistical dependence between first and second-order PMD

We measure the first and the second-order polarisation mode dispersion (PMD) in high-PMD fiber, and determine correlation between the first and second-order PMD. Theory and measurements are in a good agreement. We follow a definition of two second-order components of second order PMD: component parallel to PMD vector, called polarization dependent chromatic dispersion (PCD), and perpendicular to the PMD vector component, causing depolarization. We investigate the statistics of both components of second order PMD vector as functions of differential group delay.