Optical nonlinearity of CdSe microcrystallites in a sputtered SiO2 film

Abstract
Optical nonlinearity of a sputtered SiO2 film containing CdSe microcrystallites with an average diameter of 15 Å is measured by degenerate four‐wave mixing (DFWM) experiments. An effective nonlinear cross section σeff of 1.4×10−16 cm2 is obtained. The DFWM signal as a function of the probe delay time shows biexponential behavior with a fast decay time of 10 ps and a slow decay time of 60 ps, which give fast and slow carrier recombination times as 20 ps and 120 ps. The third‐order susceptibility ‖χ(3)‖ is estimated to be 1.3×10−8 esu. The photodarkening and laser annealing effects which are serious problems for device applications are not observed.