Distributed optical data bus for board-level interconnects

A design for a distributed free-space optical system is presented that provides interconnection of electronic processing elements at the board level of packaging. The system can be expanded to more than two boards and transfers an array of data in parallel between connection planes. The design uses binary optic microlens arrays to collimate and collect light from surface-emitting lasers, and it uses substratemode holographic window elements for directing light to and from the bus region. The use of a collection lens array for extending the alignment tolerance of the imaging system is also discussed. The paper concludes with experimental demonstrations of critical system components and performance with 64-bit data arrays.