Are crossbars really dead? The case for optical multiprocessor interconnect systems

A recent innovation in fiber optic devices has led to a new implementation of crossbar switches that does not share the same problems while retaining the full advantages of a crossbar switch. This innovation is an optical and-gate that can be used to demultiplex multiple high speed data streams that are carried on one common optical medium. Optical time domain multiplexing (OTDM) can combine the data from many nodes and broadcast the result back to all nodes. This paper discusses OTDM technology only to the extent necessary to understand its characteristics and capabilities. The main contribution lies in the description and analysis of interconnect architectures that use OTDM to achieve a level of performance that is beyond electronic means. It is expected that cost-reduced OTDM systems will become competitive with the next generation of interconnect systems.