Building Data Centers With Optically Connected Memory

Future data centers will require novel, scalable memory architectures capable of sustaining high bandwidths while still achieving low memory access latencies. Electronic interconnects cannot meet the challenges presented by the need for multi-terabit off-chip memory data paths. In this work, the electronic bus between main memory and its host processor is replaced with a circuit-switched optical interconnection network. We investigate the impact of our optically connected memory system on large-scale architectures and experimentally validate the protocol using field-programmable gate array based processor nodes and a custom-designed memory controller. The processor communicates all-optically with multiple synchronous dynamic random access memory nodes using 4 × 2.5-Gb/s wavelength-striped payloads, operating error free with bit-error rates less than 10-12.