Optical nonlinearities of Fe2O3 nanoparticles investigated by Z-scan technique

Abstract The single beam Z-scan technique has been used to measure the third-order nonlinear refractive index, γ, the two-photon absorption coefficient, s, and the variation of refractive index per unit photoexcited carrier density σ r , and the free carrier absorption cross section σ ab for quantum-confined Fe 2 O 3 nanoparticles coated by a layer of organic molecular in toluene and bare particles in hydrosol. For coated Fe 2 O 3 nanoparticles, the ratio γ/s is enhanced by a factor of five compared to the bare sample. Their figures of merit related to linear and two-photon absorption for ultrafast all-optical devices application were determined.