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Abstract: Monoclinic 2at% Eu-doped KY(WO4)2 is grown by top-seeded solution growth method. Polarization-resolved absorption and stimulated-emission cross-section spectra are determined for this crystal. Spectroscopic properties of Eu:KY(WO4)2 are modeled within conventional Judd–Ofelt theory, as well as theory of f–f transition intensities for systems with anomalously strong configuration interaction, yielding absorption oscillator strengths, luminescence branching ratios and radiative lifetime of 5D0 state. The impact of excited-state absorption from this state on possibility of laser operation is discussed. Photoluminescent properties of Eu:KY(WO4)2 are determined. This crystal provides intense red emission with CIE coordinates x=0.670, y=0.329. [Copyright &y& Elsevier]

Abstract: Novel oxyfluoride glass doped with YbF3 and Eu2O3 is synthesized in the SiO2–PbO–PbF2–CdF2 system by melt-quenching technique. Its physical properties, as well as the optical absorption of Eu3+ and Yb3+ ions are studied. Spectroscopic properties of Eu3+ ions are modeled within modified Judd–Ofelt theory, yielding absorption oscillator strength, luminescence branching ratios and radiative lifetime of 5D0 state. Intrinsic emission of Eu3+ ions under direct excitation in the UV, as well as up-conversion luminescence under near-IR excitation via cooperative energy transfer, 2Yb3+ →Eu3+, are studied. In the latter case, the glass provides intense reddish-orange emission with CIE coordinates x =0.636, y =0.363. The asymmetry parameter R for Eu3+ emission in the studied glass is about 8. The efficiency of this transfer mechanism is estimated from shortening of 2F5/2(Yb3+) lifetime to be 10±1%. [Copyright &y& Elsevier]

Abstract: Pure and Nd-doped disordered calcium vanadate Ca10K(VO4)7, Ca10Li(VO4)7, Ca9La(VO4)7 and Ca9Y(VO4)7 single crystals with high optical quality were grown by Czochralsky technique in inert atmosphere. Their polarized absorption spectra were investigated in details. Spectroscopic parameters for Nd3+ ion were determined with Judd–Ofelt theory (J–O) and theory of f–f transition intensities for systems with intermediate or anomalously strong configuration interaction (ICI or ASCI approximation). Spectral and temporal characteristics of luminescence associated with 4F3/2→4I9/2, 4I11/2 and 4I13/2 transitions were analyzed, luminescence branching ratios and radiative lifetimes were calculated. Thermal expansion coefficients were determined for Ca9La(VO4)7 and Ca9Y(VO4)7 crystals in the directions of a and c crystallographic axes. Principal thermo-optic coefficients dn o/dT and dn e/dT were measured for Ca9La(VO4)7 crystal in the spectral range of 0.4–1.1μm. The potential of disordered vanadates for laser applications was analyzed from the point of thermal effects. [Copyright &y& Elsevier]