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Abstract Eu3+-doped Bi 4 Ge 3 O 12 (BGO) single crystal with the size of Ø2 × 83 mm3 was successfully grown by the micro-pulling-down method. The absorption cross section, emission cross section and Judd–Ofelt analysis of Eu:Bi 4 Ge 3 O 12 (Eu:BGO) were reported for the first time. The absorption cross-section is 1.03 × 10−20 cm2 with full-width at half-maximum of 3.1 nm at around 393 nm. The spectroscopic intensity parameter Ω t (t = 2,4,6), radiative transition probabilities, branching ratios and radiative lifetime were obtained, respectively. Furthermore, the stimulated emission cross-section centered at 611 nm was calculated to be 6.32 × 10−21 cm2. The fluorescence lifetime of 5D 0 level was obtained to be 1.51 ms. The results indicate that Eu: BGO single crystal could be a potential laser host in the visible range. [ABSTRACT FROM AUTHOR]

Titanium doped sapphire (Ti:Al 2 O 3 ) crystal fibers have been grown by the micro-pulling-down (μ-PD) method using different pulling rate in the range (0.1–0.5 mm/min). The present work has investigated the crystal growth, including diameter, bubbles defects and segregation properties. The fiber’s absorption and IR emission experiments are analyzed. The lifetime of Ti 3+ in the IR range obtained at room temperature is 3.1 μs. Moreover, the two blue emissions at 420 nm and 470 nm bands have been discussed. [ABSTRACT FROM AUTHOR]

Yb,Tb:YAG crystals with various Yb3+ and Tb3+ concentration were grown by the micro-pulling-down method (μ -PD). The absorption spectra, fluorescence spectra and fluorescence decay curves of Yb,Tb:YAG crystals were measured at room temperature. Under 980 nm excitation, Yb,Tb:YAG crystals exhibited intense visible up-conversion luminescence due to the cooperative energy transfer from two Yb3+ ions to one Tb3+ ion. Under 485 nm excitation, Yb,Tb:YAG crystals yielded near-infrared down-conversion emission, ascribing to the cooperative absorption of pumping photons and cooperative energy transfer from one Tb3+ ion to two Yb3+ ions. The energy transfer processes from Yb3+ ions to Tb3+ ions were discussed, and the energy transfer efficiency was calculated. Based on studies of the obtained results, Yb3+/Tb3+ co-doped YAG crystal shows promising potential for sensing, volumetric displays, optical data storage, light emitting diodes. • Yb,Tb:YAG single crystals grown by the micro-pulling-down technique. • The cooperative energy transfer process was analyzed. • The effect of doped concentration on energy transfer efficiency was discussed. [ABSTRACT FROM AUTHOR]

Tm3+, Pr3+ co-doped Bi 4 Ge 3 O 12 (Tm,Pr:BGO) crystals with various Pr3+ doping concentration were successfully grown using the micro-pulling-down (μ-PD) method. The use of Pr3+ co-doping for deactivating the Tm3+ ions at 1.5 μm emission was investigated in the BGO single crystal for the first time. The effect of Pr3+ concentration on the spectroscopic properties of Tm,Pr:BGO crystals were demonstrated. In addition, the fluorescence lifetime of Tm3+:3F 4 level of 0.5 at.% Pr, 2 at.% Tm:BGO crystal was quenched effectively (from 5.64 ms down to 0.36 ms) and the population inversions between Tm3+:3H 4 and 3F 4 levels are enhanced to achieve a four-level laser system at 1.5 μm. • Tm,Pr:BGO crystals with different Pr3+ concentration were grown using by the micro-pulling-down method. • The effect of Pr3+ concentration on the spectroscopic properties of Tm,Pr:BGO crystals was studied. • The use of Pr3+ co-doping for deactivating the Tm3+ ions at 1.5 μm emission was investigated in BGO crystal. [ABSTRACT FROM AUTHOR]

A Nd:BGSO crystal with the dimensions of Φ2 × 131 mm3 has been grown successfully by the micro-pulling-down method. The peak absorption cross-section at 808 nm was calculated to 0.98 × 10−20 cm2 with full-width at half-maximum of 17.4 nm. The stimulated emission cross-section was obtained to be 3.15 × 10−20 cm2 at 1063 nm. The fluorescence and radiative lifetimes of 4F 3/2 level were 248 μs and 300 μs respectively. All results indicate that the Nd: BGSO single crystal would be a promising near-IR solid-state laser material. [ABSTRACT FROM AUTHOR]

Photograph of Yb,Ho:YAG crystals grown by the μ-PD method. (a) Yb = 0.05, (b) 0.1, (c) 0.15. • Y 3 Al 5 O 12 (YAG) single crystals doped with a fixed Ho3+ content of 0.5 at.% and various Yb3+ contents (Yb = 5, 10 and 15 at.%) have been successfully grown by the micro-pulling-down (μ-PD) method. Y 3 Al 5 O 12 (YAG) single crystals doped with a fixed Ho3+ content of 0.5 at.% and various Yb3+ contents (Yb = 5, 10 and 15 at.%) have been successfully grown by the micro-pulling-down (μ-PD) method. The absorption spectra, fluorescence spectra and fluorescence decay curves were recorded at room temperature. The intense emission of Yb,Ho:YAG crystal centered at 2 μm corresponds to the 5I 7 → 5I 8 transition. Three intense emissions centered at 524–569 nm, 623–691 nm and 744–746 nm, correspond to the 5F 4 + 5S 2 → 5I 8 , 5F 5 → 5I 8 and 5F 4 + 5S 2 → 5I 7 transitions, respectively. The possible energy transfer mechanisms were discussed intensively. [ABSTRACT FROM AUTHOR]

Nd3+ doped Y 3 Sc x Al 5-x O 12 (x = 0.05, 0.5, 1) single crystals were successfully grown by the micro-pulling-down (μ-PD) technique. The effect of compositional parameter x on the structure, absorption, emission and fluorescence lifetime of Nd:Y 3 Sc x Al 5-x O 12 crystals was studied. The Nd3+ concentration in the core increased with increasing of compositional parameter x. The full width at half maximum (FWHM) of the emission band centered at 1064 nm was calculated to be 6.1, 7.1, and 7.3 nm for x = 0.05, 0.5 and 1, respectively. The fluorescence lifetimes of 4F 3/2 levels are 259.3, 269.6, and 276.9 μs for x = 0.05, 0.5, and 1, respectively. The results indicate that the Nd:Y 3 Sc x Al 5-x O 12 crystals are promising materials for laser output. • Nd:Y 3 Sc x Al 5-x O 12 crystals were successfully grown by the micro-pulling-down technique. • Spectral parameters of Nd:Y 3 Sc x Al 5-x O 12 crystals were obtained. • The effect of composition on the structure and spectral parameters was discussed. [ABSTRACT FROM AUTHOR]

Dy3+-doped Y 3 Al 5 O 12 (YAG) and Y 3 ScAl 4 O 12 (YSAG) single crystals have been successfully grown by the micro-pulling-down (μ-PD) technique for the first time. The room temperature absorption spectra, fluorescence spectra and fluorescence decay curves were measured. Dy:YAG and Dy:Y 3 ScAl 4 O 12 crystals exhibit strongest emission centered at 583 nm, corresponding to the 4F 9/2 → 6H 13/2 transition. The decay lifetime of the 4F 9/2 level was measured to be 634 μs and 667 μs, respectively. All these results indicate that the Dy:YAG and Dy:Y 3 ScAl 4 O 12 crystals are promising candidates for yellow laser operation. • Dy:YAG and Dy:YSAG crystals were grown by the micro-pulling-down method. • Dy:YAG and Dy:YSAG crystals exhibit strong emission centered at 583 nm. • Dy:YSAG crystal has a wide emission bandwidth due to the disordered crystalline structure. [ABSTRACT FROM AUTHOR]