The core of silicon photonics PICs uses a silicon-on-insulator (SOI) wafer, where a thin silicon layer acts as the waveguide core surrounded by a buried oxide insulation layer. Silicon photonics is the study and application of photonic systems which use silicon as an optical medium. The silicon is usually patterned with sub-micrometre precision, into microphotonic components. By Christoph Kopp, Ségolène Olivier, and Stéphane Bernabé Silicon photonics is widely considered a key enabling technology. Silicon photonics (SiPh) is an advanced technology that merges silicon-based semiconductor manufacturing with photonic components for data transmission, processing, and sensing. Thereby it opens a route towards very advanced PICs with very high yield and low cost. By leveraging existing semiconductor infrastructure and know-how, silicon photonics enables highly advanced PICs with.