Polarization mode dispersion in highly birefringent optical fibers

Summary form only given. Over the past few years the major limitation of transmission speed in telecommunication single mode fiber optic systems is polarization mode dispersion (PMD). Although polarization effects in optical fibers have initially played a minor role in the development of lightwave systems their importance has recently enormously grown. It is due to enormous increase In optical path lengths, which can be achieved with single-mode fibers, and also increase in bit rates in digital systems. Real single-mode fibers as used in telecommunication possess nonzero internal birefringence and two orthogonally polarized modes have randomly different phase velocities, inducing fluctuations of the polarization state of the light guided in the fiber. Moreover, real single-mode fibers experience bends, twists, stresses, inhomogeneities, and imperfections that induce additional birefringence and simultaneously affect the two polarization states of the light guided in the fiber differently. These produce a nonzero level of internal birefringence, a difference between the refractive indices experienced by light of both orthogonal polarizations. The birefringence varies randomly along the fiber, leading to PMD.