Optical waveguides in silicon for optical interconnects

As an optical material single crystal silicon exhibits certain properties which, when coupled to an extremely mature processing technology which is dimensionally compatible with integrated optics, makes it very attractive for waveguide realisation. Low absorption loss in the 1.3-1.5 μm wavelength band, simple control of the refractive index by doping, electrical/optical control of the refractive index by free carrier injection/generation and straightforward waveguide fabrication by chemical (wet) and plasma (dry) etching are attributes which are beginning to stimulate the development of waveguiding in silicon. Thus the use of silicon itself as the waveguiding medium, as opposed to the use of oxidised silicon as a substrate on top of which other waveguide materials are deposited, has become an alternative approach to the realisation of intra-chip optical interconnection