Free carrier absorption loss of p-i-n silicon-on-insulator (SOI) phase modulator

Silicon high-speed waveguide-integrated electro-optic modulator is one of the critical devices for on-chip optical networks. The device converts data from electrical domain to the optical domain. Most studies for high speed modulation method in Si or Si based device are based on free carrier concentration variations (injection or depletion of free carriers) which are responsible for local refractive index variations and then phase modulation of a guided wave traveling through the active region. A change in the refractive index/absorption can be achieved by injection or depletion of both electron and holes into the intrinsic region of a silicon p-i-n diode.