Ion implantation as a tool in the synthesis of practical third-order nonlinear optical materials

It is now well-established that metal nanocrystal composites with attractive third-order non-linear optical properties can be synthesized in various dielectric hosts by ion implantation, ion exchange, sol–gel processes, sputtering, and pulsed-laser deposition. Whether these are appropriate to make practical all-optical switching and wave-guiding devices remains to be seen; however; in particular, techniques for the fabrication of simple device structures based on these materials are largely unexplored. This paper reviews the optical physics of the third-order non-linearity in metal nanocrystal composites, to illustrate how material parameters of both quantum dots and host matrix affect the optical non-linearities. The figures of merit that characterize simple building blocks—such as wave-guide resonators and directional couplers—for all-optical switching circuits are discussed. Novel ways of using ion implantation to enhance the properties of layered nanocluster and nanocrystalline materials are considered, particularly those that complement techniques for building up optical heterostructures, such as ion exchange, sputtering and pulsed-laser deposition.