Influence of matrix on third order optical nonlinearity for semiconductor nanocrystals embedded in glass thin films prepared by Rf-sputtering

CdSe nanocrystals were successfully embedded in high index glass films by rf-sputtering technique. All films showed the shift of absorption edge to shorter wavelength compared with that of bulk CdSe, so-called, blue shift, and it was evident that there is a quantum confinement effect in the films. The amount of the blue shift depended on the kind of matrix glass as well as the size of embedded CdSe nanocrystals. The third-order optical nonlinearity evaluated by Z-scan technique also depended on the matrix glass. The larger nonlinearity was observed from the matrix glass with higher refractive index. In addition, it was found that the value of shift of absorption edge, or the quantum confinement effect was linearly related to the third-order nonlinearity for CdSe nanocrystals embedded in glass thin films.