Contribution of the Two-Photon Absorption to the Third Order Nonlinearity of Au Nanoparticles Embedded in TiO₂ Films and in Ethanol Suspension

Abstract

We measured the absorptive and refractive nonlinearities in Au nanoparticles when they are embedded in a TiO 2 film and when they are suspended in ethanol. The morphology of the nanoparticles was estimated by using HRTEM microscopy. Different contributions related to electronic polarization and two-photon absorption were observed in the samples using a self-diffraction technique with pulses of 26 ps at 532 nm. Transmittance experiments were performed in order to confirm the mechanisms of optical absorption. The Au nanoparticles were grown by the photoreduction of TiO 2 sol-gel solutions which contain Au 3+ ions. The thin films were prepared by using the dip coating technique with fresh UV exposed sol-gel solutions. We observed that when the sample does not present any important nonlinear absorption it is possible to enhance the participation of the nanoparticles in the optical Kerr response of the media.

Optical Kerr effect exhibited by carbon nanotubes and carbon/metal nanohybrid materials

“…The TWM system was previously calibrated using Carbon Disulfide (CS 2 ) deposited in a quart cuvette with a thickness of 1 mm, as a nonlinear medium with a well known third-order nonlinear susceptibility of 3 χ ( ) ¼ 1.9 Â 10 À 12 esu [21]. The fitting of the nonlinear optical results was achieved by using the expression for describing the amplitudes of the transmitted fields that have been derived elsewhere [35]: …”

Chaotic Signatures Exhibited by Plasmonic Effects in Au Nanoparticles with Cells

“…Titanium dioxide solid films with Au NPs were prepared by a sol-gel method [33]. The Au NPs were synthesized in situ through direct radiation in the laboratory.…”

Mechano-optical transmittance and third order nonlinear optical properties exhibited by Au nanoparticles

“…The preparation of the Au NPs was carried out by a sol-gel processing route previously described [19]. Within the process a TiO 2 sol-gel precursor solution was employed.…”