NONLINEAR ABSORPTION AND RETRACTION OF QUANTUM-CONFINED INP NANOCRYSTALS GROWN IN POROUS-GLASS

Single-beam Z-scan experiments have been used to measure the two-photon absorption coefficient β and bound electronic nonlinear refractive index γ of composites of InP nanocrystals grown in 40 and 150 Å Vycor porous glass. These materials were also studied with two-beam time-resolved Z scans to confirm that the nonlinearities are instantaneous with respect to the ∼100 ps pulses used. The magnitudes of the nonlinearities in the 150 Å sample are found to be similar to those of bulk InP when scaled by the volume fraction of deposited material. For the 40 Å sample the ratio γ/β is enhanced by a factor of fourteen compared to bulk InP.© 1995 American Institute of Physics.