Thin silica-titania films containing inclusions of CdS semiconductor microcrystals have been produced by the sol-gel technique. A large blue shift (62 nm) of the absorption edge is observed and attributed to quantum confinement in the nanometer size microcrystals. High negative nonlinearity (n2 ? - 310-8 cm2/kW) has been found in these films. We report on measurements of the wavelength dependence of this nonlinearity. In particular a high negative nonlinear refractive index has been observed for pump photon energies located near the bandgap and between the bandgap and half the bandgap. The nonlinear refraction index shows a slow decrease in time attributed to oxidation of the semiconductor.
Nonlinear properties of semiconductor-doped silica sol-gel films
S Pelli;
1995
Abstract
Thin silica-titania films containing inclusions of CdS semiconductor microcrystals have been produced by the sol-gel technique. A large blue shift (62 nm) of the absorption edge is observed and attributed to quantum confinement in the nanometer size microcrystals. High negative nonlinearity (n2 ? - 310-8 cm2/kW) has been found in these films. We report on measurements of the wavelength dependence of this nonlinearity. In particular a high negative nonlinear refractive index has been observed for pump photon energies located near the bandgap and between the bandgap and half the bandgap. The nonlinear refraction index shows a slow decrease in time attributed to oxidation of the semiconductor.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
