Photorefractive nano-crystalline silicon: Materials, science, and application

In recent years the prospect of engineering an integrated photonic technology based on amorphous siliconbased has focused efforts on providing a unified understanding of the optical properties of this material. From a optical properties prospective the science of amorphous silicon is most transparent from a nanocrystalline material framework. Of particular interest for photonic engineering is the tunable range of the refractive index in amorphous silicon, the fast and slow light induced changes in epsilon 1 and 2, the means by which to deposit films of sufficient thickness and smoothness for the photonic application and the relationships among deposition conditions, material properties, and in particular the optical parameters. The present work reviews some of the previous work and examines the experimental and theoretical basis for the fast light induced refractive index change with the hope of providing the insight needed for device engineering. This work suggests several novel designs for light amorphous silicon based light valves and other devices.