An Optical Carry Chain Fast Adder

Abstract

A significant problem in Arithmetic Unit design and particularly for systolic arrays remains the speed attainable in achieving high speed addition. The root of the problem is carry propagation and a method is presented which is relatively independent of word length. The problem is addressed by the description of a suggested radical design involving a hybrid optical and electronic approach. The method of carry chain addition through pass gates is explained and a suggested implementation utilising Fabry-Perott resonators, optical waveguides and voltage controlled couplers is described. The design is suitable for n-stage modular expansion.