Analysis of the ellipticity and general scaling perturbation induced PMD   in a transmitting fiber
  Presented is an analysis of general scaling perturbations in a transmitting fiber. For elliptical perturbations, under some conditions an intermode dispersion parameter characterizing modal PMD is shown to be directly proportional to the mode dispersion. 
Maksim Skorobogatiy, Mihai Ibanescu, Steven Johnson, Ori Weisberg,   Torkel Engeness, Steven Jacobs, Yoel Fink