Efficient optical interconnections for data-center computing systems

Abstract

Within the past decade, the semiconductor computing industry has developed multicore and multithreaded core processors to overcome the challenges and shrinking benefits of traditional technology scaling. Multichip systems built using these components will require immense amount of off-chip bandwidth and low latency chip-to-chip links at the lowest energy cost possible. Wavelength-division multiplexed (WDM) silicon photonics have the potential to provide a solution for this immense interconnect problem. At Oracle, we are aggressively building a portfolio of active and passive nanophotonic devices, circuits, and multichip packaging with the aim to achieve sub-picojoule per bit communication links between computing elements in a large array “Macrochip”. To achieve ultralow energy consumption will certainly require integrating best-in-breed photonic devices with electronic circuits. While the juxtaposition of silicon photonic devices and VLSI circuits on the same silicon substrate represents the most intimate integration of electronic and photonic technologies, achieving this will require an immense amount of sophistication in design and process integration. Instead, hybrid integration of aggressive components, built on individually optimized technology platforms, is a pragmatic approach to achieving peak performance. Such “photonic bridge” chip components may be used as units in a larger transmitter or receiver array or as drop-in communication physical layer elements in a multi-chip computing node.