Abstract

Terrestrial lightwave system performance is continuing its long history of ever-increasing single-fiber capacity (almost 3 orders of magnitude in the last decade). In the postdeadline session of OFC '96, three groups described systems transmitting more than 1 Tbit/sec through a single fiber 40 to 150 km long. The systems all employed wavelength-division multiplexing (WDM) using multiple channels with bit-rates between 20 and 100 Gb/sec. These systems, with total band- widths ranging from 20 to 33 nm, are starting to be limited by the ~35-nm bandwidth of eibium amplifiers. When multiple amplifier spans are employed, gain equalization becomes an important issue as well. Thus wide-bandwidth amplifiers are needed for high- capacity systems; and gain-flattened amplifiers will be needed to transmit these capacities over long distances. These heady capacities were surpassed during the postdeadline session of ECOC '96 by an experiment achieving 2.6 Tbit/sec over 120 km of conventional fiber. For this demonstration, which used 132 20-Gb/s channels covering a total bandwidth of 35 nm, it became necessary to employ duobinary modulation to reduce the individual channel bandwidths. Given the eibium gain-bandwidth limitations, it is likely that future improvements in single-fiber capacity will be achieved through reduced-bandwidth modulation formats and/or by use of different, wider-bandwidth amplifiers such as Raman amplifiers.

© 1996 Optical Society of America