Free space optical message routing for high performance parallel computers

We survey various electrooptical message routing systems for sending N messages between N processors and discuss the theory and practice of these systems. In particular, we compare these proposed systems with respect to various metrics including time, space, number of switches, bandwidth, energy, as well as estimates to scalability and cost in current technology. There are two classes of interconnection networks for parallel computers: multistage networks and single stage networks. Optical multistage networks are often the optical realization of conventional multistage electronic networks. Optical single stage networks use free space optical routing techniques to achieve a virtual crossbar. We describe various optical single stage networks based on some quite diverse techniques including matrix-vector multiplication, various dynamic and static holographic methods, as well as frequency multiplexing