Integrated Optics in Silicon

Silicon is an attractive platform for the integration of optical components because of the mature infrastructure dedicated to the fabrication of silicon microelectronic devices. Furthermore, the silicon optical components can be readily integrated with transistors to form complex signal processing systems. At the wavelengths most relevant for optical communication (near 1550 nm), silicon has a high index and low inherent loss, making it an ideal material for compact devices. However, such compact devices also have large scattering loss. In addition, the electro-optic effects are weak in silicon, making it difficult to realize active components. This talk will describe techniques, such as smoothing and selective waveguide widening, for reducing scattering loss to enable the fabrication of high-Q filters and low-loss waveguides. The seminar will discuss three types of optical modulators, based on thermal index modulation in a silicon waveguide, carrier-based index modulation in a PIN diode waveguide structure, and a silicon-compatible electro-active organic crystal waveguide.
Michael W. Geis

MASSACHUSETTS INSTITUTE OF TECHNOLOGY
LINCOLN LABORATORY