Recent progress in silicon-based optical waveguide switches

Optical switches are key components for applications in 1.31/1.55 mu m optical communications, networks and microsystems. They can reduce the cost of the network and increase fiber transmission capacity and at the same time, distribute optical signals to different subscribers. Optical switches in Si-based waveguides make use of changes in the refractive index induced by carrier injection and offer advantages of small device size, polarization independence and capability of integrating with other Si-based optoelectronic devices. By adding Ge into Si, the bandgap of SiGe shifts towards the optical communication wavelength while the refractive index increases, which is good for wave guiding. P-N junction can also be formed easily during SiGe epitaxy. In this paper, six switching approaches at the optical communication wavelength will be introduced.