Recent progress in high-capacity long-haul WDM systems

Summary form only given. The trend in lightwave transmission systems is towards higher bit rates, higher powers, longer span lengths, and the incorporation of optical fiber amplifiers to replace regenerators. This trend brings with it a number of technical challenges. Optical fibers present limitations due to loss, dispersion, and nonlinearities. Optical amplifier performance is constrained by parameters such as bandwidth, gain magnitude and flatness, output power, and noise figure. In general, capacity upgrades can be accomplished by increasing single-channel bit rates, and by wavelength-division multiplexing (WDM) high-speed channels. Both strategies can be implemented simultaneously. This talk outlines the technical challenges facing amplified lightwave systems, which incorporate WDM techniques, and reviews recent experiments.