High Speed, High Capacity Bused Interconnects using Optical Slab Waveguides

In this paper we consider the use of optical slab waveguides as buses in a parallel computing environment. We show that slab buses can connect to many more elements than conventional electrical or ber optic buses. We also introduce a novel multiplexing scheme called mode division multiplexing that vastly increases the number of independent channels that a single slab can support. We show that optical slab waveguides have, in principle, capacities of over a million independent channels (distinguished by about 1000 \out-of-plane modes" and about 1000 wavelengths) in a single physical medium, with each channel capable of sustaining a load of over 1000. This becomes comparable to the high capacity of a free space optical system, but with the ability to broadcast each light source to many physically separated locations. Preliminary experiments on the \sawtooth slab bus" point to the feasibility of practical slab buses. We also present a bus arbitration example that uses the high capacity and loading of slab buses to achieve sublogarithmic arbitration