Silicon photonics for the visible and near-infrared spectrum

Emerging applications in quantum information, microscopy, biosensing, depth sensing, and augmented reality demand miniaturized components in the visible (VIS) and near-infrared (NIR) spectrum with wavelengths between 380 and 1100 nm. Foundry silicon photonics, which has been optimized for telecommunication wavelengths, can be adapted to this wavelength range. In this article, we review recent developments in silicon photonics for VIS and NIR wavelengths, with a focus on platforms, devices, and photonic circuits fabricated in foundries. Foundries enable the creation of complex circuitry at a wafer scale. Platforms based on silicon nitride and aluminum oxide wave-guides compatible with complementary metal–oxide–semiconductor (CMOS) foundries are becoming available. As a result, highly functional photonic circuits are becoming possible. The key challenges are low-loss waveguides, efficient input/output coupling, sensitive detectors, and heterogeneous integration of lasers and modulators, particularly those using lithium niobate and other electro-optic materials. These elements, already developed for telecommunications, require further development for λ < 1100 nm. As short-wavelength silicon photonics technology advances, photonic integrated circuits can address a broader scope of applications beyond O- and C-band communication.