Silicon Photonics for Exascale

With the extraordinary growth in parallelism at all system scales driven by multicore architectures, computing performance is increasingly determined by how efficiently high bandwidth data is communicated among the numerous compute resources. High-performance systems are especially challenged by the growing energy costs dominated by data movement. As future computing systems aim to realize the Exascale regime – surpassing 1018 operations per second – achieving energy efficient high bandwidth communication becomes paramount to scaled performance. Silicon photonics offers the possibility of delivering the needed communication bandwidths to match the growing computing powers of these highly parallel architectures with extremely scalable energy efficiency. However, the insertion of photonic interconnects is not a one-for-one replacement. The lack of practical buffering and the fundamental circuit switched nature of optical data communications require a holistic approach to designing system-wide photonic interconnection networks. New network architectures are required and must include arbitration strategies that incorporate the characteristics of the optical physical layer. This paper reviews the recent progresses in silicon photonic based interconnect devices along with the system level requirements for Exascale. We present a codesign approach for building silicon photonic interconnection networks that leverages the unique optical data movement capabilities and offers a path toward realizing future Exascale systems.