Nanophotonic devices for power-efficient communications

Power-efficient high-speed nanophotonic silicon devices, particularly silicon modulators, are the key components for optical communications. Design of active silicon photonic devices involves trade-offs between different performance metrics. Here we review these trade-offs and current state-of-the-art active silicon photonics devices. We also introduce emerging approaches for improving the performance via device design, including the use of vertical PN junctions for improving modulation strength, as well as novel device designs that allow for fabrication tolerance and temperature fluctuation. Finally we describe material integration approaches that expand the available modulation mechanisms and open new possibilities for high-performance active devices. The set of materials includes Ge, GeSi, III-V materials, organic and inorganic materials, and two-dimensional materials.