Acoustically-controlled optical Kerr effect signals in bimetallic Au-Pt nanoparticles embedded in a TiO2 thin film

Nonlinear optical measurements for detecting acoustical waves were carried out in bimetallic Au-Pt nanoparticles embedded in a TiO2 thin solid film. The samples were prepared by a sol-gel method. A two-wave mixing technique was employed to explore the third order nonlinear optical properties exhibited by the nanocomposites. Interferometric measurements sensitive to acoustical perturbations were studied in the samples. The modification in the index of refraction of the nanocomposites induced by vectorial nanosecond optical irradiations was comparatively evaluated. Additionally, a single-beam transmittance experiment confirmed the absence of any important multi-photonic absorption process during our measurements. An optical Kerr effect was identified to be the main responsible effect for the third order optical nonlinearities induced by nanosecond pulses at 532 nm wavelength. It is considered that advantages in acousto-optical transduction by nonlinear optical interactions can give rise to potential development of quantum information acquisition systems and high-speed sensors. Moreover, low-dimensional acousto-optical functions in nanostructured materials can be contemplated.