Optical network technologies for HPC: Computer-architects point of view

Optical network technologies, such as circuit switching, wave-length division multiplex and silicon photonics, have been considered for high-performance computing (HPC) systems to achieve low communication latency, high link bandwidth and low power consumption. However, conventional HPC systems still use packet networks with electric switches. Only active optical cables for inter-cabinet long links are borrowed from optical network technologies. This paper firstly reviews the gap between the conventional HPC networks and feasible optical network technologies. We explain our pessimism that this gap will continue to exist by the beginning of the post-Moore era, i.e. 2025–2030. It secondly illustrates our research vision that HPC networks will be able to adopt optical circuit switching, possibly using free-space optics in the post-Moore era.