Chapter 6 - Polarization effects

Abstract

In this chapter we focus on the polarization effects and consider the coupling between the two orthogonally polarized components of an optical field induced by the nonlinear phenomenon known as cross-phase modulation (XPM). The origin of nonlinear birefringence is discussed first in Section 6.1. It is followed with the derivation of a set of two coupled NLS equations that describes evolution of the two orthogonally polarized components of an optical pulse inside a fiber. The XPM-induced nonlinear birefringence has several practical applications discussed in Section 6.2. The next section considers nonlinear polarization changes with focus on polarization instability. Section 6.4 is devoted to the vector modulation instability occurring in birefringent fibers. In contrast with the scalar case discussed in Section 5.1, the vector modulation instability can occur even in the normal-dispersion regime of a birefringent fiber. Section 6.5 considers the effects of birefringence on solitons. The last section focuses on polarization-mode dispersion (PMD) in fibers with randomly varying birefringence along their length and its implications for lightwave systems.