Baojuan Sun

Fluorescence properties of trivalent europium doped in various niobate codoped glasses

A series of niobate–phosphate and niobate–silicate glasses doped with Eu3+ ions were prepared. The emissions, phonon-side band spectra, and fluorescence lifetimes of these glasses were studied and the intensity parameters of Eu3+ were obtained. The temperature dependence of emission intensity of the Eu3+ ion in these niobate glasses was investigated. The temperature-quenching rates were determined. The results indicate that in niobate glasses, as the concentration of Nb2O5 increases, the covalence becomes stronger, the symmetry becomes lower and the electron-phonon coupling strength becomes stronger. Thus, the lifetimes become shorter, and the nonradiative transition processes and the temperature-quenching effect become stronger.

Ultraviolet light-induced spectral change in cubic nanocrystalline Y2O3:Eu3+

Abstract Ultraviolet light-irradiation induced spectral change was studied in cubic nanocrystalline Y 2 O 3 :Eu 3+ . Under the irradiation of the ultraviolet lights separated from xenon lamp, the excited charge transfer band of Eu 3+ decreased after irradiation. The smaller the particle size and the shorter the wavelength, the larger the spectral change. It was attributed to the local structural change surrounding Eu 3+ ions in/near the surface. Under the irradiation of the 266-nm pulsed laser, some Eu 3+ in nanoparticles was reduced to Eu 2+ .

Light-induced change of charge transfer band in one europium doped aluminosilicate glass

Abstract Ultraviolet light-induced spectral change in one Eu3+ doped aluminosilicate glass was studied. It was observed that the excited charge-transfer band decreased after irradiation. The intensity at the irradiated site decreased linearly with the power density of the irradiation light. This means that the light-induced change is a one-photon process. Irradiations at different wavelengths indicate that the spectral change is frequency-selective. The dark decay of the spectral change was also studied. At least two time constants were obtained. One constant is ∼2.5 h, and the other is longer.

Theory and experiment of two-photon 'direct' interference for type-II spontaneous parametric down-conversion with an ultrafast pulse laser pump

Fourth-order spatial interference of entangled photon pairs generated in the process of spontaneous parametric down-conversion pumped by a femtosecond pulse laser has been performed for the first time. In theory, it takes into account the transverse correlation between the two photons and is used to calculate the dependence of the visibility of the interference pattern obtained in Young’s double-slit experiment. In this experiment, a short focal length lens and two narrow band interference filters were adopted to eliminate the effects of the broadband pump laser and improve the visibility of the interference pattern under the condition of nearly collinear light and degenerate phase matching.