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By controlling the oxygen pressure, single-phase CuO and CuO thin films have been obtained on quartz substrates using a pulsed laser deposition technique. The structure properties and linear optical absorption of the films were characterized by X-ray diffraction and UV-VIS spectroscopy. By performing z-scan measurements using a femtosecond laser (800 nm, 50 fs), the real and imaginary parts of the third-order nonlinear susceptibility, Re χ and Im χ, of the films were determined. Both CuO and CuO films exhibited large optical nonlinearities, which is comparable to those in some representative semiconductor films such as ZnO and GaN films using femtosecond laser excitation. Compared with CuO films, the CuO films showed larger third-order nonlinear optical effects under off-resonance excitation. Furthermore, the mechanisms of the optical nonlinearities in CuO and CuO films are explained in the main text. It was suggested that the reasons of the difference in their nonlinear refractive effects may be related to the different electronic structure in CuO and CuO materials. [ABSTRACT FROM AUTHOR]

Abstract: Single-phase β-FeSi2 thin films have been grown on quartz substrates using femtosecond laser deposition (800nm, 50fs, 1KHz) under gas pressure of 3.0×10−4 Pa. X-ray diffraction (XRD) and field-emission scanning electron microscopy (SEM) were used to determine the structural properties and surface images of the films. Typical XRD patterns of the film showed that no other diffraction peak except β-FeSi2 was found. The SEM results indicated that the films were composed of well-distributed grains, in the range 50–150nm in diameter. In addition, normal incidence spectral transmittance and reflectance data suggested that the β-FeSi2 film has a direct energy gap of about 0.85eV. The thickness of the layer and the refractive index of the film were determined by performed calculation in the wavelength range 1.9–2.7μm. Furthermore, the Raman spectra of the films were also discussed. [Copyright &y& Elsevier]

Abstract: Single-phase β-FeSi2 thin films were prepared on Si(100) and Si(111) wafers by using femtosecond laser deposition with a FeSi2 alloy target for the first time. X-ray diffraction (XRD), field scanning electron microscopy (FSEM), scanning probe microscopy (SPM), electron backscattered diffraction pattern (EBSD), and Fourier-transform Raman infrared spectroscopy (FTRIS) were used to characterize the structure, composition, and properties of the β-FeSi2/Si films. The orientation of β-FeSi2 grains was found to depend on the orientation of the Si substrates, and photoluminescence at wavelength of 1.53 μm was observed from the single-phase β-FeSi2/Si thin film at room temperature (20 °C). [Copyright &y& Elsevier]

High‐energy, few‐cycle laser pulses are essential for numerous applications in the fields of ultrafast optics and strong‐field physics, due to their ultrafast temporal resolution and high peak intensity. In this work, different from the traditional hollow‐core fibers and multiple thin solid plates, the generation of an octave‐spanning supercontinuum broadening is demonstrated by utilizing multiple ultrathin liquid films (MTLFs) as the nonlinear media. The continuum covers a range from 380 to 1050 nm, corresponding to a Fourier transform limit pulse width of 2.5 fs when 35 fs Ti: sapphire laser pulse is applied on the MTLFs. The output pulses are compressed to 3.9 fs by employing chirped mirrors. Furthermore, a continuous high‐order harmonic spectrum up to the 33rd order is realized by subjecting the compressed laser pulses to interact with Kr gas. The utilization of flowing liquid films eliminates permanent optical damage and enables wider and stronger spectrum broadening. Therefore, this MTLFs scheme provides new solutions for the generation of highly efficient supercontinuum and nonlinear pulse compression, with potential applications in the fields of strong‐field physics and attosecond science. [ABSTRACT FROM AUTHOR]

Different thickness of Na 2/3 Ni 1/4 Mn 3/4 O 2 thin films were deposited on stainless steel substrates by pulsed laser deposition technique. X-ray diffraction and field-emission scanning electron microscope results reveal that the thin film with highly preferred c-axis orientation is composed of homogeneous nano-sized grains. The charge/discharge tests indicate that the 0.55 μm thick film demonstrates a high initial discharge capacity of 175.3 mAhg −1 and a retention of 91% after 30 cycles at a current density of 13 mAg −1 . Furthermore, as the current density increases from 13 to 130 mAg −1 , about 89% of its initial discharge capacity can be maintained, exhibiting excellent rate capability. These superior electrochemical properties would promote Na 2/3 Ni 1/4 Mn 3/4 O 2 thin film to be a promising cathode material for sodium-ion micro-batteries. [ABSTRACT FROM AUTHOR]

Aluminium oxide (Al2O3)-modified LiNi0.5Mn1.5O4 (LNMO) thin-film electrodes were prepared by pulsed laser deposition and effects of surface modification on interfacial reactions of LNMO were studied. The modification by Al2O3 was carried out successively after the deposition of LNMO thin-film. Field-emission Scanning Electron Microscope results show that Al2O3 disperses uniformly in nano-scale on the film electrodes. Charge/discharge behavior of the batteries under a high cutoff voltage of 4.9V vs. Li is highly improved by using Al2O3 modification, especially at elevated temperature. The electrochemical properties of LNMO thin-film electrodes are also affected by the thickness of coating. It is found that 20nm thick Al2O3 coating layer improves thermal stability most obviously among them. At 55°C, 84.1% of its initial capacity at 1C-rate can be retained after 100 cycles, and as the rate increases from 0.2 to 10C the reversible capacity can still maintain 80.7mAhg−1, which are greatly improved compared to pristine, 6 and 40nm thick Al2O3 modified samples. [ABSTRACT FROM AUTHOR]

Abstract: CuO nanocrystalline thin films are deposited on quartz substrates by pulsed laser deposition. The grown single-phase CuO films are characterized by X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The optical nonlinearity of CuO films is investigated by the Z-scan method under a high-repetition-rate (HRR) femtosecond laser (800nm, 50fs, 80MHz). The CuO nanocrystalline films are found to be good optical limiters with a limiting threshold of 0.3GW/cm2 and a damage threshold of 1.65GW/cm2. The possible mechanisms of the optical limiting are also proposed. [Copyright &y& Elsevier]

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: 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: Anatase phase TiO2 films have been grown on fused silica substrate by pulsed laser deposition technique at substrate temperature of 750°C under the oxygen pressure of 5Pa. From the transmission spectra, the optical band gap and linear refractive index of the TiO2 films were determined. The third-order optical nonlinearities of the films were measured by Z-scan method using a femtosecond laser (50fs) at the wavelength of 800nm. The real and imaginary parts of third-order nonlinear susceptibility χ (3) were determined to be −7.1×10−11esu and −4.42×10−12esu, respectively. The figure of merit, T, defined by , was calculated to be 0.8, which meets the requirement of all-optical switching devices. The results show that the anatase TiO2 films have great potential applications for nonlinear optical devices. [Copyright &y& Elsevier]

Abstract: Copper oxide, Cu2O and CuO, thin films have been synthesized on Si (100) substrates using pulsed laser deposition method. The influences of substrate temperature and oxygen pressure on the structural properties of copper oxide films were discussed. The X-ray diffraction results show that the structure of the films changes from Cu2O to CuO phase with the increasing of the oxygen pressure. It is also found that the (200) and (111) preferred Cu2O films can be modified by changing substrate temperature. The formation of Cu2O and CuO films are further identified by Fourier transform infrared spectroscopy. For the Cu2O films, X-ray photoelectron spectroscopic studies indicate the presence of CuO on the surface. In addition, the optical gaps of Cu2O and CuO films have been determined by measuring the transmittance and reflectance spectra. [Copyright &y& Elsevier]

Abstract: Zinc oxide (ZnO) thin films have been grown on Si (100) substrates using a femto-second pulsed laser deposition (fsPLD) technique. The effects of substrate temperature and laser energy on the structural, surface morphological and optical properties of the films are discussed. The X-ray diffraction results show that the films are highly c-axis oriented when grown at 80°C and (103)-oriented at 500°C. In the laser energy range of 1.0mJ–2.0mJ, the c-axis orientation increases and the mean grain size decreases for the films deposited at 80°C. The field emission scanning electron microscopy indicates that the films have a typical hexagonal structure. The optical transmissivity results show that the transmittance increases with the increasing substrate temperature. In addition, the photoluminescence spectra excited with 325nm light at room temperature are studied. The structural properties of ZnO films grown using nanosecond (KrF) laser are also discussed. [Copyright &y& Elsevier]

Abstract: The effects of experimental parameters such as substrate temperature, laser intensity and pressure of oxygen on the structural properties of zinc oxide (ZnO) films using femtosecond laser deposition were studied in this paper. The c-axis-oriented ZnO films were obtained under the optimized conditions with the temperature of substrate and the pressure of oxygen being 80°C and 1×10−3 Pa, respectively. The structural properties were analyzed by X-ray diffraction and surface morphology of films was analyzed by field-emission scanning electron microscopy, and the results showed that the prepared films are of fine grains (30–50nm) and of even density. Furthermore, the optical transmissivity of annealed ZnO films were also studied in the range from 200 to 900nm. [Copyright &y& Elsevier]