DISPERSION-MANAGED SOLITONS AND OPTIMIZATION OF THE DISPERSION MANAGEMENT

We overview recent progress in dispersion-managed (DM) fiber optic com munications. Wavelength-division-multiplexing transmission of a DM sol iton (or more general return-to-zero (RZ) formatted data) is an attrac tive way to realize middle- and long-distance ultra-high-capacity fibe r communication systems. We present a theory of the DM optical soliton and a simple basic theory of the general DM RZ transmission. Two ordi nary differential equations for the root-mean-square pulse width and c hirp (momentum equations) describe the fast (during compensation perio d) evolution of the DM pulse. Applying chirped Gauss-Hermite orthogona l functions we derive a path-averaged propagation equation governing b oth the shape of the DM soliton and the slow (average) evolution of an y chirped DM pulse. We describe the breathing dynamics of the self-sim ilar core and oscillating tails of the DM optical pulse propagating in a fiber line with an arbitrary dispersion map. Based on the developed theory we describe the basic system principles, the design, and the o ptimization rules for DM fiber links. We demonstrate how to determine the energy enhancement of the DM soliton and optimal (chirp-free) poin ts for launching of the signal, and how to evaluate the characteristic s of a carrier signal for specific system parameters. DM solitons in s ystems with in-line filtering and Bragg gratings are also studied. Ana lytical results are illustrated by numerical simulations for a number of specific dispersion maps actively used in practice. (C) 1998 Academ ic Press.