Properties of nonblocking single-substrate optical space switching networks constructed from directional couplers.

Some of the properties of single-substrate nonblocking optical space switching networks that are constructed from directional couplers, waveguide bends, and waveguide crossovers are considered. Expressions are given for the ratio of network output signal to cross talk, insertion loss, and total switch count for ten different structures. Based on these expressions, estimates of the maximum switch sizes attainable are made. Consideration is also given to the factors that govern the practical implementation of such structures, and this shows that rearrangeably nonblocking single-substrate switches of up to 128 × 128 should be possible if technologies other than Ti:LiNbO(3) are used.