PUMP PROBE Z-SCAN STUDIES OF GAAS NANOCRYSTALS GROWN IN POROUS-GLASS/

Time-resolved pump/probe Z-scan experiments using 1064 nm, 100 ps dura tion pulses were performed to determine the temporal characteristics o f the optical nonlinearities of quantum confined GaAs nanocrystals dop ed in Vycor glass. The build-in and decay of the nonlinearities are in stantaneous with respect to the excitation pulses. Single-beam Z-scan experiments were also used to measure the two-photon absorption coeffi cient, beta, and bound electronic nonlinear refractive index, gamma, o f the quantum confined nanocrystals. The ratio gamma/beta is enhanced by a factor of approximately ten compared to bulk GaAs.