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This research investigates the mechanism of the optical dispersive wave (DW) and proposes a scheme that can realize an efficient wavelength conversion. In an elaborately designed photonic crystal fiber, a readily available ytterbium laser operating at ~1 μm can be transferred to the valuable 1.3 μm wavelength range. A low-order soliton is produced to concentrate the energy of the DW into the target wavelength range and improve the degree of coherence. The input chirp is demonstrated to be a factor that enhances the wavelength conversion efficiency. With a positive initial chirp, 76.6% of the pump energy in the fiber can be transferred into a spectral range between 1.24 and 1.4 μm. With the use of a grating compressor, it is possible to compress the generated coherent DW of several picoseconds into less than 90 fs. [ABSTRACT FROM AUTHOR]

In this paper, 80GeO2-8Ga2O3-10BaO-2Nb2O5-6PbO (in mol%) glass samples with different Tm2O3 concentrations (0, 0.5, 0.75, 1, 1.25, and 1.5 mol. %) were prepared by traditional meltquenching method. According to the measurement of thermal properties of the host glass, the glass transition temperature is 596.7 °C and no crystallization peak is observed. Judd-Ofelt parameters Ωt (t=2, 4, 6) and fluorescent lifetimes were obtained by Judd-Ofelt theory. The similar values of Judd-Ofelt parameters and the full-width at half-maximums of ~1800 nm indicate the local environment of Tm3+ changes little with increment of Tm2O3 concentrations. Maximum stimulated emission cross-section of ~1800 nm is 6.22×10-21 cm² as calculated by Fuchtbauer-Ladenburg formula. Energy migration among Tm3+ ions was analyzed by the extended overlap integral method. The non-radiative transition rates between mainly energy levels of Tm3+ were calculated. Non-radiative transition rate of ³F4 energy level caused by OH was analyzed by rate equation and deduced by fitting the fluorescence decay curve. [ABSTRACT FROM AUTHOR]

Abstract Nanocrystalline La0.8Pb0.2FeO3 has been prepared by the sol-gel method. XRD patterns show that the nanocrystalline La0.8Pb0.2FeO3 is a perovskite phase with the orthorhombic structure and its mean crystallite size is about 19 nm. The influence of Pb ions which replaced the La ions on A-sites can be directly observed from the electrical and sensing properties to H2 gas. The conductance of La0.8Pb0.2FeO3-based sensor is considerably higher than that of LaFeO3-based sensor, and Pb-doping can enhance the sensitivity to H2 gas. An empirical relationship of with α = 0.668 was obtained. [ABSTRACT FROM AUTHOR]