Bandwidth of a single-mode optical fiber in PSK coherent optical transmission systems

Abstract

The author examines propagation characteristics of PSK modulated signal light under the influence of the group velocity dispersion (GVD), the higher-order dispersion (HOD), and the nonlinear refractive index of a single-mode fiber. Emphasis has been placed on behavior at and near the zero-dispersion wavelength (ZDWL), where the HOD as well as the GVD would be important. It is found that propagation at the ZDWL is similar to that away from the ZDWL; the effect of the nonlinear refractive index can be comfortably ignored. The effect of HOD is found to induce self-amplitude modulation (SAM) at the ZDWL; the amplitude of PSK-modulated light becomes modulated as the light travels down the fiber. The SAM considered produces a power penalty in the PSK coherent fiber transmission, and determines the dispersion limit of such systems. As the operating wavelength moves away from the ZDWL, the effect of GVD becomes important relative to that of HOD. The significance of the results is examined. >