Nonlinear dynamics for all-optical 3R regeneration

Abstract

All-optical 3R (retiming, reshaping, reamplification) regeneration is expected to become a key enabling technology for 40 Gb/s long-haul transport systems. There are two basic building blocks for an all-optical 3R regenerator: a clock recovery circuitry and a nonlinear optical gate. We focus on technologies for all-optical recovery and provide an overview of mechanisms for nonlinear optical gating. We have demonstrated all-optical clock recovery using self-pulsing two-section gain-coupled distributed feedback (DFB) lasers. Self pulsation in two-section gain-coupled DFB lasers is a result of existence of two modes in one of the sections. Continuous tuning of self-pulsation frequencies from 11 to 120 GHz has been demonstrated by proper design of the laser structure. Three modes of clock recovery operation using the two-section DFB lasers are described. The nonlinear gating mechanisms that we briefly describe include cross-gain, cross-phase modulation using SOAs, cross-absorption modulation using electro-absorption modulation, and nonlinear directional coupling.