Towards Energy-Efficient Photonic Interconnects

In this work, we improve the energy-efficiency of silicon-photonic interconnects for many-core processors. The high optical loss of nanophotonic components and low wall-plug efficiency of laser sources results in high laser power consumption. In addition, ring-heaters consume a significant amount of power to keep the ring resonators in a constant operating temperature, which is required to maintain the optical communication. We propose a laser control scheme that saves power by turning off the lasers when predicting low interconnect activity and by judiciously scaling the width of the communication link based on predictions of the expected message length. We also evaluate an insulation method that reduces the impact of localized heating induced by highly-active components on the 3D-stacked logic die.