d the associated delays are +/- tau/2. For N-mode fiber, you can either set the modulus (DGD property) or specify the actual delays (tau property) In random mode, model draws from a chi distribution with &lt;# of modes&gt; degrees of freedom for actual modulus of PMD vector (Maxwell if N=2).</p>
<p>Main method: Delays are applied as shifts to randomly oriented principal modes. See J. P. Gordon and H. Kogelnik, "PMD fundamentals: Polarization mode
dispersion in optical fibers," Proc. Natl. Acad. Sci., vol. 9