Specialty Optical Fibers Handbook

In essence, these are the same phenomena that generate polarization mode

dispersion (PMD), for the simple reason that birefringence and PMD are

essentially one and the same thing.

2

In the real world, in which fibers cannot reasonably be protected from

environmental stress (temperature fluctuations, etc.), it is necessary to use a

purpose-designed PM fiber. PM fibers are engineered in such a way that the

two orthogonally polarized modes are forced to travel at different velocities (i.e.,

with different propagation constants). This difference in velocities makes it very

difficult for optical energy to cross-couple, with the result that the polarization ...