3D OPTICAL INTERCONNECTS FOR HIGH-SPEED INTERCHIP AND INTERBOARD COMMUNICATIONS

Metal connections are generally considered the most basic obstacle to continued advances in the speed of computing systems. The bottleneck o f current metal-based interconnection networks is typically their very limited bandwidth. Optics, with its inherent parallelism, high bandwi dth, freedom from planar constraints, and noninterfering communication , has been recognized as a possible solution to the communication prob lem in high-performance computing systems. This article proposes a mod el of 3D free-space optical interconnection network architectures for chip-to-chip and board-to-board communications. The model is intended to provide sufficiently high communication bandwidth as well as the pa rallelism required by massively parallel computing systems. Ln the mod el, interprocessor links are provided by free-space optics, eliminatin g all electrical links between processors. This results in a denser re alization of processor arrays as well as higher interconnect densities than with electrical approaches. The authors show how to embed binary n-cube and mesh networks into the model and how to physically realize the binary n-cube network an the basis of the proposed embedding meth odology using computer-generated holograms. As a relatively immature t echnology, optics has some disadvantages, but these are technology dep endent and not fundamentally insurmountable. Ongoing research will eve ntually point the way to improved performance of optical switches and converting devices.