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Abstract: Pr3+, Yb3+ co-doped CaYAlO4 (Pr, Yb: CYA) single crystal was grown using the Czochralski (CZ) method. For near-infrared quantum-cutting system, a quantum efficiency of 145% for Pr3+, Yb3+-codoped CYA crystal has been obtained by ignoring the nonradiative losses. Under excitation at 940nm, high intensities of 502nm, 555nm, 628nm, 661nm and 729nm emissions turn up. Fluorescence decay time of 3P0→3F2 emission of Pr3+ ions and 2F5/2→2F7/2 transition of Yb3+ ions were also studied as evidences for energy transfer. [Copyright &y& Elsevier]

Abstract: Sm:CaNb2O6 single crystal has been grown by the Czochralski method. Its high-temperature X-ray powder diffraction, optical absorption, emission spectroscopic as well as lifetime have been studied. Thermal expansion coefficients (α), J–O parameters (Ω i ), radiative lifetime (τ rad), branching ratios (β) and stimulated emission cross-sections (σ e) were calculated. The quantum efficiency (η) was calculated to be 97%. The intense peak emission cross section at 610, 658nm were calculated to be 2.40×10−21, 2.42×10−21 cm2. These results indicate that Sm:CaNb2O6 crystal has potential use in visible laser and photonic devices area. [Copyright &y& Elsevier]

High quality Pr3+ single-doped PbF 2 and Pr3+/Yb3+ co-doped PbF 2 single crystals were grown by temperature gradient technique (TGT). By co-doping Yb3+ ion as Pr3+ ions sensitizer, the visible light emission can be regulated and the largest luminescence branching ratio can be switched from red-orange to blue-green light. Besides, when Pr3+ ions doping concentration is as low as possible, the blue light self-absorption effect can be weakened, which is beneficial to high-efficiency blue laser output. Moreover, the broad band emission around 1.3 μm from 1G 4 energy level can be observed in the Pr3+/Yb3+:PbF 2 crystal with the low maximum phonon energy for the first time. Absorption, emission spectra and luminescence mechanism are well analyzed by the energy transfer process and J-O theory. The laser upper energy level lifetime of Pr3+ ions has a great increase by Yb3+ ion effect. These advantageous spectroscopic characteristics show that the Pr3+/Yb3+:PbF 2 crystal might be potential laser gain materials for blue-green and ∼1.3 μm near-IR laser operation. • By co-doping Yb3+ ion as sensitizer for Pr3+ ions, the visible light emission can be regulated and the largest luminescence component ratio can be changed from red-orange light to blue-green light. • When doping concentration of Pr3+ ion is as low as possible, the self-absorption effect of blue light can be weakened, which is beneficial to high-efficiency blue laser output. • The broad band emission around 1.3 μm from 1G 4 energy level can be observed in the Pr3+/Yb3+: PbF 2 crystal with the low maximum phonon energy for the first time. [ABSTRACT FROM AUTHOR]

Abstract: Spectroscopic measurements of the calcium niobate CaNb2O6 single crystal doped with samarium ions were performed. Polarized absorption and emission spectra as well as luminescence decay curves of this material were recorded as a function of temperature in the 5–300K temperature region. Analysis of low temperature spectra made it possible to determine energies of crystal field components of Sm3+ multiplets involved in the excitation and luminescence phenomena. Number of crystal field levels derived implies that Sm3+ ions in the CaNb2O6 host are accommodated in several different sites. Radiative lifetime of the 4G5/2 metastable level determined based on the Judd–Ofelt analysis of room temperature absorption spectra amounts to 777μs, a value close to that of luminescence lifetime determined from luminescence decay curve. Energy transfer between the NbO6 group and samarium ions was observed in wide temperature range. Intense luminescence related to the 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions centered at 610nm and 660nm, respectively, combined with strong absorption band near 404nm that matches perfectly the pump light provided by commercial InGaN/GaN diode lasers points at a potential of CaNb2O6:Sm3+ for the design of all-solid-state visible lasers. [Copyright &y& Elsevier]