Abstract
This chapter illustrates that optical information processing techniques have shown remarkable promise over all-electronic techniques for computation-intensive applications. Optical computing systems can allow two- and three-dimensional interconnections, non-interfering communication, and ultrahigh switching speed. The main thrust in optical computing research is, thus, being geared toward the development of alternate algorithms and architectures to exploit all the advantages that optics can offer. Symbolic substitution has been proposed as a very powerful means for implementing optical computing operations. This technique exploits the parallelism of optics to first perform spatial search for all the occurrences of a particular pattern and then replace all occurrences of this pattern with another pattern. Symbolic substitution requires a coherent source for recognition and substitution.