SMT-compatible optical-I/O chip packaging for chip-level optical interconnects

The rapid increase in Internet data traffic requires large-scale switching systems that have high-bandwidth and high-density board-to-board, board-to-backplane and chip-to-chip interconnections within the system. This paper describes one solution for implementing an economical chip-to-chip optical interconnection. The basic concept is as follows; 1) Silicon ASICs are hybrid integrated with GaAs optoelectronic devices by bump bonding, 2) optoelectronic packages are surface-mounted on a printed circuit board (PCB), 3) optical paths for connecting chips are implemented as an interlayer of the PCB, and 4) a wide and collimated optical beam couples the chip and the board through a narrow air gap. Since it can replace high speed electronic wiring by optical at the chip-level and also there are no optical fibers or connectors on the board, this optical-I/O chip packaging has the potential to bring revolutionary change in optoelectronic packaging