Tutorial on NRZ, RZ, or Solitons: Modulation Format, Your Choice or the Fiber´s?

Summary form only given. Since the invention of the erbium fiber amplifier made possible all-optical transmissionover distances significantly longer than the length of spans between electronic regenerators, transmission line designers were confronted with a whole new design space. Parameters like dispersion, self-phase modulation, four-wave mixing, and optical noise (added as a field) became important. In the all-optical transmission line, some modulation formats, for instance FSK and PSK worked poorly, while others, like solitons, which were not appropriate with electronic regenerators, became possible.