Impact of optical amplifiers on lightwave communications

Abstract

The field of lightwave communications is undergoing a revolution brought about by recent achievements in optical amplifier technology. Erbium-doped fiber amplifiers (EDFAs) permit a variety of system architectures that facilitate greater access to the vast transmission capacity inherent in optical fibers, thereby providing significantly increased networking functionality and operational flexibility for both terrestrial networks and undersea-cable systems, all potentially at lower cost than at present. The features of EDFAs specific to the various applications include: high saturation power as transmitter power amplifiers, low-noise operation as receiver preamplifiers, a wide gain spectrum for amplifying a large number of wavelength-division-multiplexed (WDM) signals, and linear gain for analog amplification. Equally important, their simple construction utilizing reliable semiconductor pump lasers will allow system planners to design communications networks having substantially enhanced reliability. It can be said that lightwave communications is now passing from a replacement phase to a revolutionary phase, and the fiber optical amplifier is the catalyst in this transformation.