Large enhancement of the third-order optical susceptibility in Cu-silica composites produced by low-energy high-current ion implantation

Low-energy high-current ion implantation in silica at a well-controlled sub strate temperature has been used to produce composites containing a large c oncentration of spherical Cu clusters with an average diameter of 4 nm and a very narrow size distribution. A very large value for the third-order opt ical susceptibility, chi ((3))=10(-7) esu, has been measured in the vicinit y of the surface plasmon resonance by degenerate four-wave mixing at 585 nm . This value is among the largest values ever reported for Cu nanocomposite s. Additionally, the response time of the nonlinearity has been found to be shorter than 2 ps. The superior nonlinear optical response of these implan ts is discussed in terms of the implantation conditions. (C) 2001 American Institute of Physics.