Dispersion-Managed Solitons and Chirped Return to Zero: What Is the Difference?

Publisher Summary This chapter provides an insight of the evolution of soliton transmission to its present incarnation as the dispersion managed soliton (DMS) transmission and the evolution of nonreturn to zero (NRZ) transmission to its present incarnation as the chirped return to zero (CRZ) transmission. The interest in using solitons is because of their remarkable property that they do not spread in the time domain because of dispersion or in the frequency domain because of nonlinearity. A single soliton pulse in an ideal, lossless fiber is completely stable. Both the approaches depend on an optimization of modulation format, dispersion mapping, and nonlinearity. Essentially, the DMS and the CRZ pulses exhibit different characteristics that suit them to different applications. CRZ produces pulses that merge in transit along a wide undersea span and reform only at the receiver ashore, while DMS produces pulses that reform periodically, thereby permitting access at intermediate add or drops. In the modern day WDM systems, the CRZ format has a substantially longer reach than the traditional NRZ format, and the quasilinear DMS format appears to be the only soliton format without strong control that is compatible with today's fibers and components.