Abstract

Today’s super computers are limited with respect to bandwidth of the interconnections, crosstalk, and lack of connectivity. Optical communication technology is able to offer solutions to these problems, provided that the architectures of future computers can take full advantage of this potential. Optics offers the capability of connecting thousands of data channels at extremely high bandwidths with virtually no crosstalk. But, optical systems are naturally space invariant whereas present-day computers are interconnected irregularly or, in optical terms, space variant. Symbolic substitution is a simple and yet powerful logic system which facilitates the design of architectures with regular interconnections and circuits with constant fan-in and constant fan-out, thus simplifying the demands on optics and optical logic gates. The elementary operations in symbolic substitution logic are transformations on binary patterns. Every transformation can be decomposed conceptually into three operations: pattern recognition, regeneration, and pattern substitution. Recognition and substitution are based on conventionally free space optics. The regeneration requires just optical nonlinearity, not bistability. Examples demonstrate how this logic can be used to implement elementary operation for computing, such as binary arithmetic, a latch, and a Turing machine.

© 1986 Optical Society of America