Effect of optical fiber birefringence on long-distance soliton transmission

Abstract

It is often stated that soliton propagation in optical fibers is modeled mathematically by the nonlinear Schrodinger equation which has soliton solutions. However, real fibers contain many nonidealities that lead to changes in the mathematical models that must be used to study them. These effects include nonconservative phenomena such as attenuation which must be compensated or Raman, Brillouin, and Rayleigh scattering which must be made negligible. These effects also include conservative phenomena such as higher-order dispersion and birefringence. These effects are benign and can typically be ignored. The reasons why conservative effects are benign can be understood by an analogy to simple nonlinear springs. The equations that model birefringent optical fibers are described, and self-trapping is demonstrated. Finally, a model of randomly varying birefringence is obtained. It is shown that, at lowest order in an appropriate perturbation expansion, the usual nonlinear Schrodinger equation results, while at higher order there is a slight depolarization.