Three-dimensional board-to-board free-space optical interconnects and their application to the prototype multiprocessor system: COSINE-III.

A prototype multiprocessor system using three-dimensional board-to-board free-space optical interconnects is constructed for the first time to our knowledge. In the system, 64 processing units form a three-dimensional mesh processor network with the help of bidirectional board-to-board free-space optical interconnects. A theoretical analysis shows that the three-dimensional board-to-board freespace optical interconnects effectively solve common interconnection problems such as wiring congestion, signal delay, and clock skew. The prototype system, COSINE-III, is confirmed to work well as a multiprocessor system. The system is also shown to be easy to extend to a larger and more flexible system.