Device engineering for silicon photonics

Silicon photonics has attracted increasing attention and research effort in recent years because of its potential for low-cost integration using existing complementary metal–oxide–semiconductor technology. One motivation for research on silicon photonics has been its potential application in energy-efficient high-speed optical interconnects for computing systems, particularly in circumstances where large power dissipation from electrical interconnects will limit performance. The high-density integration of photonic devices, the wide availability of fabrication facilities and the potential for monolithic integration with electronic circuits offer the prospect for future low-cost, reliable and energy-efficient silicon photonic devices suitable for applications in computing, communications and sensing. Herein we review recent progress in the engineering of new devices and functional elements in silicon photonics, including low-loss waveguides, passive integrated devices, integrated lasers, modulators, photodetectors and fiber–chip coupling techniques. We also identify some emerging opportunities with potential for future development, such as mid-infrared silicon photonics and optomechanical devices, and summarize some current trends, including the development of photonic devices based on amorphous silicon and the use of foundries for silicon-photonic device fabrication.