Designing Chip-Level Nanophotonic Interconnection Networks

Technology scaling will soon enable high-performance processors with hundreds of cores integrated onto a single die, but the success of such systems could be limited by the corresponding chip-level interconnection networks. There have been many recent proposals for nanophotonic interconnection networks that attempt to provide improved performance and energy-efficiency compared to electrical networks. This paper discusses the approach we have used when designing such networks, and provides a foundation for designing new networks. We begin by briefly reviewing the basic silicon-photonic device technology before outlining design issues and surveying previous nanophotonic network proposals at the architectural level, the microarchitectural level, and the physical level. In designing our own networks, we use an iterative process that moves between these three levels of design to meet application requirements given our technology constraints. We use our ongoing work on leveraging nanophotonics in an on-chip title-to-tile network, processor-to-main-memory network, and dynamic random-access memory (DRAM) channel to illustrate this design process.