Review of competing technologies for multigigabit ultralong-span fiber optic communication systems

Advances in conventional technologies are reviewed first. The contributions of various components, namely optical amplifiers, external modulators, tunable and narrow-linewidth lasers, high-sensitivity and high-speed detectors, and dispersion-shifted fibers, to the realization of higher speed and longer span fiber communications are discussed. The effect of techniques such as time-division and wavelength-division multiplexing, coherent detection, and dispersion compensation is explored. Optical soliton transmission is then reviewed as an alternative technology. Finally, mid-infrared communications based on new fluoride fibers and associated transmitters and receivers are considered. The author's opinions on the prospects for each approach, in the context of their limitations, are presented.