Scalable Network Architectures Using the Optical Transpose Interconnection System (OTIS)

The Optical Transpose Interconnection System (OTIS) proposed by Marsden et al. (Opt. Lett.18, 13 (July 1993), 1083–1085) makes use of free-space optical interconnects to augment an electronic system by adding nonlocal interconnections. In this paper, we show how these connections can be used to implement a large-scale system with a given network topology using small copies of a similar topology. In particular, we show that, using OTIS, an N² node 4-D mesh can be constructed from N copies of the N-node 2-D mesh, an N² node hypercube can be constructed from N copies of the N-node hypercube, and an (N², α², c/2) expander can be constructed from N copies of an (N, α, c) expanders, all with small slowdown. Finally, we show how this expander construction can be used to build multibutterfly networks in a scalable fashion.