Silicon is the basic material of microelectronics. Transistors and circuits with structure sizes in the domain of a millionth part of a millimeter are manufactured in highly complex processes. But thanks to mass production theses methods have become considerably cheap. The standard production technique today is the so called CMOS technology (Complementary Metal Oxide Semiconductor.)

In photonics the situation is quite different. Instead of using electrons photonics uses light, photons, for information transmission and processing. But these photonic technologies are based not on silicon but a different material system, mostly Gallium arsenide (GaAs). Low volumes and relatively high costs limit the marketable applications. For a long time it was common understanding that for physical reasons silicon could not be used for photonics. But this has changed lately and silicon photonics has become a vital research topic.