Devices which have two states of transparency to light beams have the potential of being used as two state logic devices. In this particular case, these two states are stable to perturbations and can be changed by an additional optical pulse. The authors of this proposal has been involved in the demonstration of a complete set of logic gates and clocked optical flip flops based on these devices. The logic gates perform such operations as; and, or, and nor functions and the clocked flip flop, which is able to operate in two states can be flipped from one to the other by an independent pulse (clock). A recent comment that optical logic circuits, or rather combinations of them, can be simpler in complexity than the corresponding electonic equivalents, has been noteworthy and alleviates somewhat the criticism of the relatively large size of the optical components. This research is in an area of current controversy and the author has proposed highly innovative approaches to optical signal processing questions.
