Abstract

During the past decade, research on coherent lightwave communications has been actively pursued because of the potential advantages of coherent detection in high receiver sensitivity and dense wavelength-division multiplexing (WDM) capacity. Recently, considerable efforts have been made to advance coherent communication technology from a research subject to a field-deployable transmission system; several field trial results have been reported, and more trial attempts are planned.^1–3 The major part of this paper discusses the 1.7- Gb/s frequency-shift keying (FSK) coherent regenerator design and its performance in a 1-month field trial in November 1989 using installed fiber cables connected between the Roaring Creek Station and the Sunbury Hub, Pennsylvania. The discussion emphasizes several important technical issues involved in the realization of such a field-deployable system. The rest of the paper is devoted to more recent results of long-distance transmission experiments using this system and erbium- doped fiber amplifiers.

© 1991 Optical Society of America