Silicon-Photonics Microring Links for Datacenters—Challenges and Opportunities

The rapid growth of warehouse-scale datacenters demands high-throughput optical interconnects that can span short-to-medium reach distances (< few kilometers). Microring-based silicon-photonics links with single-mode fibers are highly promising for these applications. This paper presents an analysis of microring-based links from the holistic perspective of optical devices, CMOS circuits, and system-level link budget and energy-efficiency simulations. Design considerations and tradeoffs for the receiver, transmitter, and the overall link are presented, and comparisons are made to the mainstream multimode vertical-cavity surface-emitting laser-based links with multi-mode fibers. Finally, research opportunities are highlighted for further improving the energy efficiency of single channel and wavelength division multiplexing-based silicon-photonics links.