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

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