Complex-cubic Ginzburg-Landau equation-based model for erbium-doped fiber-amplifier supported nonreturn-to-zero communications

The propagation of nonreturn-to-zero pulses, composed by a superposition of two exact shock-wave solutions of a complex-cubic Ginzburg-Landau equation linearly coupled to a linear nondispersive equation, is studied in detail. The model describes the distributed (average) propagation in a dual-core erbium-doped fiber-amplifier-supported optical-fiber system where stabilization is achieved by means of short segments of an extra lossy core that is parallel and coupled to the main one. The linear-stability analysis of the two asymptotic states of the shock wave in combination with direct numerical simulations provide necessary conditions for optimal propagation of the nonreturn-to-zero pulse. The enhancement of the propagation distance by at least an order of magnitude, under a suitable choice of the parameters, establishes the beneficial role of the passive channel. (C) 2002 Optical Society of America.