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Optical interconnections in digital systems—Status and prospects

D. Z. Tsang

In computing, trends toward parallel processing, multiprocessor computers, higher operating speeds, and larger as well as denser very large scale integrated (VLSI) circuits have provided an impetus for the development of advanced interconnection technology. Multiprocessor computer designs tend to require both a larger number and a higher density of interconnections with a higher degree of connectivity than single-processor computers. The combination of higher operating speed, longer distances, and higher density leads to problems in maintaining signal integrity because of parasitic reactances, impedance mismatches, crosstalk, dispersion, and frequency-dependent skin effect losses. Also, as chip designs become larger and denser, the so-called pinout problem, in which the number of input/output pins and pads is limited by the density of wirebonds, is of increasing concern to VLSI circuit designers.