New technologies and services such as voice-over-Internet protocol and streaming video are driving global bandwidth and traffic demand, which in turn is driving research and development on ultra-high-bandwidth optical transmission capacities (see Fig. 31.1). The clusters of points in Fig. 31.1 represent different generations of lightwave communication systems, from the original 0.8 Î¼m sources and multimoded fiber to today's erbium-doped fiber amplifier (EDFA) WDM systems and onward. The resulting "optical Moore's law" corresponds to a 10x increase in "capacity x distance" every four years, making it faster than the original Moore's law for integrated circuits! This drive to higher bandwidths is being realized on many fronts - by opening up new wavelength bands (S, L, etc.), to ever-higher WDM channel counts, density, and spectral efficiency, to higher bit rates via optical andâor electrical time division multiplexing (OTDM, ETDM). In parallel with this is the drive toward increasingly optically transparent and agile networks, toward full "photonic networks," in which ultrafast optical signals - independent of bit rate and modulation format - will be transmitted and processed from end to end without costly, slow, and bulky optical-electrical-optical conversion. All of these factors will result in a critical future demand for high-performance, cost effective, ultra-high-speed, all-optical signal processing devices.
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