Can silicon change photonics?

The electronic chip industry embodies the height of technological sophistication and economics of scale. The industry mass produces complex circuitry, boasting over one billion components at such low cost that they appear in consumer products. Fabricating inexpensive photonic components by leveraging this mighty manufacturing infrastructure has been the impetus behind the development of silicon photonics. If it can be done economically and in an energy-efficient manner, empowering silicon with optical functionality will bring optical communications to the realm of computers where limitations of metallic interconnects are threatening the industry's future. Guided by such visions and propelled by pioneering research conducted in the 1980s and 1990s, silicon photonics has enjoyed spectacular progress in the last six years. The critical size of photonic devices has been scaled to the 300 nm regime making more efficient use of water real estate. Optical amplification and lasing, once considered forbidden in silicon, have recently been demonstrated. High-speed and efficient electrical-optical conversion is being performed by production-worthy devices. Silicon's nonlinear optical properties, enhanced by tight optical confinement in Si/SiO2 structures, are producing wavelength switching and generation, which are central functions in multiwavelength communications and signal processing. This article reviews these and other exciting progress being made in silicon photonics and identified the challenges that remain on the path to commercialization.