Large saturation absorption of CdSSeTe nanocrystallites in glass measured by femtosecond Z-scan technique

The optical non-linearity of CdSSeTe nanocrystallite-doped glasses has been studied using a single-beam, femtosecond Z-scan technique. We have observe d very large absorption saturation in a composite of CdSSeTe nanocrystals i n a glass host compared with CdS or CdSe, although we have not reached the saturation limit. The wavelength and power dependence of absorption saturat ion in these composites are reported. The experimental data are interpreted by a two-level model system. A comparison is also made with other nanocrys tallite composites with different stoichiometric compositions. Copyright (C ) 2000 John Wiley & Sons, Ltd.