This work determines quantitatively for the first time, we believe, the chromatic dispersion limitations due to intersymbol interference degradations for coherent optical transmission systems with CPFSK, MSK, ASK, PSK, and DPSK modulation formats and for direct on-off keying (OOK) systems. These degradations are inherent in the information transmission process itself and cannot be eliminated without reducing the fiber chromatic dispersion or incorporating complex equalization techniques in the receiver. The limits that these degradations impose have only been approached experimentally by one group, who reported an 8-Gbit/s 68-km direct detection test1 where receiver performance was degraded by the information bandwidth. Coherent system experiments will eventually reach these limits as the modulation speed increases to multi-Gbit/s rates.
© 1988 Optical Society of AmericaPDF Article