Free-space optical interconnection of 3D optoelectronic VLSI chip-stacks

Large-scale computer and data-communication systems have reached a bottleneck in performance in recent years due to the limitations of electronic interconnections for data transfer. One potential solution is based on the use of optoelectronic device arrays for free space optical interconnects. In this paper, we present the design and implementation of a 16×16 3D distributed optoelectronic crossbar switch. The core of this system is three optoelectronic VLSI chip-stack modules, plus an optical interconnection layer. Each optoelectronic chip-stack contains 16 VLSI chips and one 16×16 VCSEL/MSM array. Each VLSI chip includes 64 electronic I/Os, 16 optical I/Os, and four 16∼16 crossbar switch. The optical interconnect layer uses a hybrid approach including micro-optics, macro-optics, and diffraction gratings. This layer has been optimized for large optomechanical tolerance. Each chipstack module is 14×14×9 mm3 and the packaged system is 108×68×110 mm3. The target performance is 16 Gb/s throughput per logic channel and 128 Gb/s bisection bandwidth. At the present time, the VLSI chips have been fabricated, functionally tested, and packaged into 3D chip-stack modules, and the optoelectronics layer has been flip-chip bonded to the 3D chip-stack. In this talk we will present the results of our component and system testing.