Photonic switching applications of two-dimensional and three- dimensional crossover networks based on 2-input, 2-output switching nodes.

A technique for transforming two-dimensional implementations of crossover networks into topologically equivalent three-dimensional implementations of crossover networks is presented. The technique is based on an operation called "fan-folding." Three different type of nodes for use in switching networks are defined: the 2-module, the (2,1,1) node, and the (2,2,2) node. Optical implementations of these nodes are then described. It is then shown that each of these nodes can be used in a two-dimensional crossover network and in a three-dimensional crossover network. The modifications required in the optical hardware that will permit the nodes to be used in each of these networks is then discussed.