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Abstract: La(Mg1/2Ti1/2)O3 was synthesized via citric acid precursor. The effect of the pH of the starting solution and the molar ratio of citric acid to total metal cations concentration CA/M on the formation of La(Mg1/2Ti1/2)O3 was studied. It is found that increasing the pH of the starting solutions and the molar ratio of citric acid to total metal cations concentration enhances the formation of La(Mg1/2Ti1/2)O3. Single-phase La(Mg1/2Ti1/2)O3 was obtained from the precursor with CA/M=1 and pH=7 at 800°C for 2h, without formation of any intermediate phase. The precursors and derived powders were characterized by DTA, TG, X-ray diffraction and Fourier transform infrared spectroscopy. [Copyright &y& Elsevier]

Abstract: The spectral properties in different concentration of Yb ions (0.5–5mol%)-doped silica glasses are explored in this paper. The glasses are prepared by traditional melting method. The absorption spectra and the fluorescent lifetime (τ f) are measured at room temperature and low temperature (18K). The stimulated cross-section (σ emi) and potential laser properties (β min, I sat, I min) are calculated based on the absorption spectra. The absorption cross-section (σ abs) are in the range 1.08×10−20– 1.18×10−20 cm2 in different glasses, the fluorescence lifetime (τ f) change from 1.9 to 1.2ms with the increase of Yb3+ concentration. The potential laser properties indicate that lead silica glass is a good host for highly Yb ion doping glass. [Copyright &y& Elsevier]

Highlights • Our fiber curvature sensor has merits of inline compact, low cost and sensitive. • Highly sensitivity −15.33 dB/m−1 in the range 3.63–4.69 m−1 is experimentally demonstrated. • Low cross sensitivity 0.018 m−1/°C implies it is insensitive to environmental temperature change. Abstract An inline fiber structure formed by a silica tube spliced between single-mode fibers has been developed and tested for curvature measurement based on anti-resonant reflecting waveguide. A Fabry-Perot resonator with leaky modes of guided light in the silica tube is formed based on anti-resonant effect in the resonant wavelengths, which results in lossy dips in the transmission spectrum. Since the transmission power of the resonant dips is sensitive to structure bending, an inline curvature sensor can be realized. Experimental results reveal a high sensitivity up to −15.33 dB/m−1 in the wide curvature range of 3.63–4.69 m−1. The proposed sensor also demonstrates a low temperature sensitivity 0.27 dB/°C implying a small temperature cross sensitivity 0.018 m−1/°C. Our sensor has its merits of compact, low cost and high sensitivity. [ABSTRACT FROM AUTHOR]

Abstract: We present the experimental and theoretical study of colored conical emission (CCE) during intense femtosecond pulses propagating in a β-barium borate (BBO) crystal. CCE revealed special nonlinear dynamics of the strong coupling between the fundamental and second harmonic pulses due to the spatiotemporal modulation instability (MI). The underlying physics of CCE involve three three-photon processes, according to which the beam angular spectra was calculated on the phase-matching conditions and accords with the experimental observation. [ABSTRACT FROM AUTHOR]

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]

Abstract: We investigate the spectrum of copper phthalocyanine (CuPc) both experimentally and theoretically, which is a potential laser protective organic absorbing dye. The observed visible absorption maximum is located at 658nm, which corresponds to a1u→eg electronic transition. We then theoretically investigate the electronic spectrum of CuPc. By setting OWFπ–π (π–π overlap weighting factor, one of the adjustable parameters in the ZINDO/S method) at 0.522, the visible absorption maximum of CuPc is precisely calculated using the ZINDO/S method. The result shows that the calculated visible absorption maximum is well consistent with the experimental value. Finally, we discuss the validity and applicability of Yuan''s calculation formula [J. Phys. Chem. A 109 (2005) 2582], and investigate the new relationship between OWFπ–π and molecular structural parameters for the other metal phthlocyanine series. [Copyright &y& Elsevier]

Abstract: The spectroscopic and fluorescent decay behaviors of Yb3+-doped SiO2–PbO–Na2O–K2O glass is reported in this work. Yb2O3 contents of 1, 1.5 and 2mol% are added into the glass. Through the measurement of absorption and fluorescence spectra, and fluorescent decay rate at room temperature and at low temperature (18K), it is found that the nonradiative decay rate of Yb3+ ions is mainly determined by the interaction between residual hydroxyl groups and Yb3+ ions. Concentration quenching effect can be omitted in this glass up to the Yb3+ ion concentration of 8.98×1020/cm3. Multiphonon decay rate is also very small because of the large energy gap between 2F5/2 and 2F7/2 levels of Yb3+ ions. [Copyright &y& Elsevier]

We calculate the photoelectron momentum distributions (PMDs) from strong-field above-threshold ionization of Ar in the co-linearly polarized two-color laser fields consisting a strong fundamental component and a much weaker second harmonic by solving the time-dependent Schrödinger equation. Utilizing the recently introduced phase-of-the-phase (PP) spectroscopy, we analyze the relative phase dependence of the PMDs of the recollision electrons and the jumps in the PP spectroscopy are observed. With the semi-classical model, we demonstrate that the phase jumps originate from the competition between the orbits where recollision occurs at different returnings. Thus, the relative contribution of the multiple-returning recollision orbits is unambiguously identified with the PP spectroscopy. Additionally, we show that the relative contribution of the multiple-returning recollision orbits depends on the laser wavelength and ellipticity. In elliptically polarized laser field, the yield of the high-energy photoelectrons favors the contribution of the second-returning recollision orbits. In 1600-nm laser field, the PP spectroscopy indicates that the relative contribution of multiple-returning recollision orbits is strongly sensitive to the electron energy. [ABSTRACT FROM AUTHOR]