Contents 1. Introduction
Intensity-modulation direct-detection (IM-DD) systems have been widely used for carriers and short-reach datacenter networks because of their simple configuration, cost effectiveness, and low power consumption. Electroabsorption modulator integrated distributed feedback (EADFB) lasers are commercially available for IM-DD systems for distances ranging from 40 to 80 km. For 80-km reach, from the viewpoints of both fiber loss and chromatic dispersion, they were limited to a certain application using a wavelength for 10-Gbit/s NRZ signals. To overcome this restriction, compensation for chromatic dispersion at or very large output power for is required.
