A General Construction for Nonblocking Crosstalk-Free Photonic Switching Networks

The graph representation G(M) of a multistage switching network M is well known. Lea [IEEE Trans Commun 38 (1990), 529–538] observed that link-disjoint paths in M correspond to node-disjoint paths in G(M). He proposed G(M) as a network by treating nodes as crossbars to transfer the node-disjoint property to the crosstalk-free property essential for photonic networks using directional couplers as components. However, such a network has its peculiarities and is not commonly used. In this paper, we will show how to take advantage of this correspondence to construct nonblocking crosstalkfree networks using the vertical stacking method. Our construction simplifies the proofs of many existing results, as well as establishing some new results. © 2003 Wiley Periodicals, Inc.