Abstract
Optical duobinary signal has narrow spectrum, tolerance to chromatic dispersion, and resistance to filter distortion. With many early patents from different organizations, optical duobinary modulation was actually invented earlier and described in a thesis by L. C. Blank. The later development of optical duobinary modulation is reviewed, including its applications for retrofitting 40-Gb/s signal into existing 10-Gb/s fiber networks.
Keywords: 40 Gb/s, duobinary modulation, fiber communication, lightwave communication, optical networking, wavelength division multiplexing