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Abstract: By performing Z-scan method with a femtosecond laser (800nm, 50fs, 1kHz), we investigated the third-order optical nonlinearities of a cuprous oxide (Cu2O) film. Single-phase Cu2O film deposited on a quartz substrate was obtained using the pulsed laser deposition technique. The structure properties, surface morphology and optical transmission spectrum were characterized by X-ray diffraction, scanning electron microscopy and double beam spectrophotometer, respectively. The Z-scan results show that the Cu2O film exhibits large nonlinear refractive index, n2 =3×10−3 cm2/GW, while the two-photon absorption coefficient, α 2 =40cm/GW, is relatively small. It implies that the Cu2O film is a promising candidate for nonlinear photonic devices. [Copyright &y& Elsevier]

Abstract: The Au/TiO2 composite films have been fabricated using the pulsed laser deposition technique. The optical transmission spectra of the films were investigated in the range from 300 to 900nm and the surface plasmon resonance peaks were observed varying from 550nm to 650nm. The optical nonlinearities of the as-deposited and annealed samples were investigated by the Z-scan method using a high-repetition-rate femtosecond laser. It was found that, for the as-deposited samples, the sign of nonlinear absorption coefficients (β) changed from negative to positive with increasing Au concentration. However, for all the annealed samples, the sign of β was found to be negative. The nonlinear responses induced by the cumulative thermal effects were suggested to contribute to this phenomenon. [Copyright &y& Elsevier]

Abstract: Titanium dioxide (TiO2) films have been fabricated on fused quartz and Si(001) substrates by pulsed laser deposition technique and the single-phase anatase and rutile films were obtained under the optimal conditions. The surface images and optical transmission spectra were investigated by scanning electron microscopy and double beam spectrophotometer, respectively. The values of optical band-gap and linear refractive index of the anatase and rutile films were determined. The optical nonlinearities of the films were measured by Z-scan method using a femtosecond laser (50 fs) at the wavelength of 800 nm. Through the open-aperture and closed-aperture Z-scan measurements, the real and imaginary parts of the third-order nonlinear optical susceptibility were calculated and the results show that the anatase phase TiO2 films exhibit larger nonlinear refractive effects compared with rutile phase. The figure of merit, T, defined by T = βλ/n 2, was calculated to be 0.8 for anatase films, meeting the requirement of T <1 and showing potential applications in all-optical switching devices. [Copyright &y& Elsevier]

Abstract: In this work we investigate the third-order optical nonlinearities in CuO films by Z-scan method using a femtosecond laser (800 nm, 50 fs, 200 Hz). Single-phase CuO thin films have been obtained using pulsed laser deposition technique. The structure properties, surface image, optical transmittance and reflectance of the films were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and UV–vis spectroscopy. The Z-scan results show that laser-deposited CuO films exhibit large nonlinear refractive coefficient, n 2 =−3.96×10−17 m2/W, and nonlinear absorption coefficient, β =−1.69×10−10 m/W, respectively. [Copyright &y& Elsevier]

Abstract: Titanium dioxide thin films have been synthesized on Si (100) substrates using pulsed laser deposition method (KrF: 248 nm, 20 ns, 5 Hz). The emission spectra of the plasma induced by ablating TiO2 target in the oxygen or argon ambient gas were analyzed. The influences of substrate temperature and ambient gas pressure on the structural properties of TiO2 films were discussed. The X-ray diffraction results show that the films deposited at 750 °C are (004)-oriented anatase phase and (110)-oriented rutile phase under the oxygen and argon pressure of 5 Pa, respectively. The scanning electron microscopy images indicate that the TiO2 films have a uniform and smooth surface and are composed of nanocrystal grains. The pure anatase and rutile phase TiO2 films are further proved by Raman spectromicroscopy. In addition, the optical transmission spectra and Fourier Transform infrared spectroscopy of the films were also studied. [Copyright &y& Elsevier]