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The absorption spectrum, fluorescence spectrum and fluorescence time of a mixed sesquioxide Nd:LuYO 3 ceramic were measured at room temperature. Judd-Ofelt theory was applied to calculate the spectral parameters of Nd:LuYO 3. The absorption cross section at 812 nm was calculated to be 0.99 × 10−20 cm2 with full width at half maximum (FWHM) of 47.69 nm. The emission cross-section at 1077 nm was calculated to be 5.24 × 10−20 cm2 with FWHM of 11.62 nm. The fluorescence lifetime and quantum efficiency of the 4F 3/2 multiplet were determined to be 228.4 μs and 85.2%, respectively. Continuous-wave (CW) laser operation of Nd:LuYO 3 ceramic was demonstrated. Simultaneous laser operation at 1075.24 and 1080.03 nm was achieved with maximum output power of 490 mW and slope efficiency of 6.36%. • Nd:LuYO3 ceramic was fabricated by solid-state reaction. • Judd-Ofelt theory was used to analyze the spectroscopic properties of Nd:LuYO 3 ceramic. • CW laser operation was performed and output power of 490 mW at the absorbed power of 9.1 W is obtained. [ABSTRACT FROM AUTHOR]

Tm3+-doped calcium niobium gallium garnet (Tm:CNGG) single crystals have been successfully grown by the micro-pulling-down (μ-PD) method. The crystal structure, absorption spectra, fluorescence spectra and lifetimes of Tm:CNGG crystals were investigated. The absorption and emission bandwidths of Tm:CNGG crystals are larger than those of other Tm3+ doped garnet crystals, which will be beneficial for laser diode (LD) pumping and ultrashort pulse generation. Additionally, continuous wave (CW) laser operation around 2 μm was achieved in the 2.0 at.% Tm:CNGG crystal by LD pumping. [ABSTRACT FROM AUTHOR]

YScO 3 single crystal co-doped with Ho3+ and Pr3+ ions has been successfully grown by the Czochralaki method. The absorption spectrum, fluorescence spectrum and fluorescence decay curve were measured at room temperature. The absorption cross section of Ho,Pr:YScO 3 at 649 nm and 1130 nm was calculated to be 0.93 × 10−20 cm2 and 0.32 × 10−20 cm2, respectively. Judd-Ofelt (J-O) theory was performed to evaluate the spontaneous emission probabilities and the radiative lifetimes. Ho,Pr:YScO 3 exhibited strong emission at 2040 nm and 2890 nm with a emission cross section of 0.80 × 10−21 cm2 and 1.22 × 10−20 cm2, respectively. The fluorescence lifetime of the Ho3+:5I 6 and 5I 7 levels were calculated to be 0.31 ms and 5.89 ms, respectively. All the results indicate that the Ho,Pr:YScO 3 crystal could be a potential laser material for 2.9 μm laser operation. • Ho3+,Pr3+ co-doped YScO 3 was grown by the Czochralski method. • The crystal structure, absorption and emission spectra were investigated. • The effect of Pr3+ on the spectroscopic properties of Ho3+ was evaluated. [ABSTRACT FROM AUTHOR]

Pr 3+ -doped YAlO 3 (YAP) single crystal was successfully grown by the Czochralski (Cz) method. Polarized absorption and polarized fluorescence spectra were measured at the room temperature. The spectroscopic parameters based on the polarized absorption spectra were calculated by Judd-Ofelt (J-O) theory for the first time. The fluorescence lifetime of 3 P 0 energy level was fitted to be 19.16 μs with the quantum efficiency of 95.8%. Through the analyzing of the spectroscopic properties, Pr:YAP crystal was demonstrated to be a promising candidate for solid state laser operation. [ABSTRACT FROM AUTHOR]

A series of 0.5 at.% Tm:Ca 1-x Y x F 2+x (x = 0, 0.01, 0.04, 0.06, 0.08, 0.12) crystals have been successfully grown by the temperature gradient technique (TGT) method. The absorption spectra, fluorescence spectra, and fluorescence decay curves were measured and analyzed at room temperature. By comparison, it is found that when the concentration of Y3+ ions reaches 8 at.%, the absorption cross section corresponding to the 3H 6 →3H 4 energy level is 2.56 × 10−21 cm2 at 793 nm, which is suitable for GaAlAs LD pumping. The J-O strength parameters Ω 2 , Ω 4 , and Ω 6 were obtained. With the incorporation of Y3+ ions, the value of Ω 4 /Ω 6 gradually increases. When the concentration of Y3+ ions reaches 8 at.%, the emission cross sections are 3.05 × 10−21 cm2 at 1476 nm, 2.56 × 10−21 cm2 at 2378 nm, and the full widths at half maximum (FWHM) are 76 nm and 195 nm, respectively. The fluorescence lifetime of 3H 4 level, the upper level of 1.5 μm and 2.3 μm, is 1.05 ms, which is very beneficial for 1.5 μm and 2.3 μm laser. • With the incorporation of Y3+ ions, the value of Ω 4 /Ω 6 gradually increases. • When the concentration of Y3+ ions reaches 8 at.%, the emission cross section is 3.05 × 10−21 cm2 at 1476 nm, 2.56 × 10−21 cm2 at 2378 nm, respectively. • The fluorescence lifetime of 3H 4 level, the upper level of 1.5 μm and 2.3 μm, is 1.05 ms, which is very beneficial for 1.5 μm and 2.3 μm laser. [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+-doped bismuth germanate crystals (Tm:BGO) with various doping concentrations of 0.5, 0.75, 1.0, 1.5, and 2.0 at.% were grown by the micro-pulling-down method (μ-PD). The effect of thulium concentration on the growth, structure, absorption spectra, emission spectra and fluorescence lifetime of 3H 4 and 3F 4 state was studied. Under excitation of 792 nm, Tm:BGO crystals exhibit two fluorescence bands corresponding to the 3H 4 → 3F 4 and the 3F 4 → 3H 6 transitions. The fluorescence lifetime of 3H 4 state decreased strongly as the thulium concentration increased, while the lifetime of 3F 4 state was relatively constant for all thulium concentrations. • Tm:BGO crystals with different Tm3+ concentration were grown by the micro-pulling-down method. • The effect of Tm3+ concentration on the growth, structure and spectroscopic properties of Tm:BGO crystals was studied. • Tm:BGO crystals exhibit two fluorescence bands corresponding to the 3H 4 → 3F 4 and the 3F 4 → 3H 6 transitions. [ABSTRACT FROM AUTHOR]

Nd:SrAl 11 O 19 (Nd:SRA) crystal has been grown by the Czochralski method. Polarized absorption spectra, polarized fluorescence spectra and fluorescence lifetime were investigated. For σ-polarization, the peak absorption cross section at 798 nm is 2.08 × 10−20 cm2 with full width at half maximum (FWHM) of 10.2 nm and the peak emission cross section is 3.36 × 10−20 cm2 at 1048.5 nm with FWHM of 4.80 nm. The Judd-Ofelt parameters Ω 2,4,6 were obtained to be 0.51 × 10−20 cm2, 2.08 × 10−20 cm2, and 2.12 × 10−20 cm2, respectively. Continuous-wave laser operation of the a-cut and c-cut Nd:SRA sample has been demonstrated. The maximum output power of 8.33 W was achieved from c-cut sample at an absorbed power of 27.73 W, corresponding to a slope efficiency of 31.3%. • Nd:SrAl 12 O 19 crystal has been gown by the Czochralski method. • Spectral parameters of Nd:SrAl 12 O 19 crystal were obtained. • Continuous-wave laser was demonstrated from Nd:SrAl 12 O 19 crystal. [ABSTRACT FROM AUTHOR]

Yb,Pr:CaF 2 crystals have been grown successfully by the temperature gradient technique(TGT). The absorption spectra, fluorescence spectra, fluorescence decay lifetime of Pr3+ ions in CaF 2 crystal sensitized by different Yb3+ ions concentration have been measured. The effective J-O intensity parameters were fitted to be Ω 2 =0.36 × 10−20cm2, Ω 4 =2.89 × 10−20cm2, Ω 6 =6.69 × 10−20cm2 for 0.3 at.%Pr,1.5 at.%Yb:CaF 2. And the emission cross sections of 3P 1 →3H 5 (535 nm), and 3P 0 →3F 4 (750 nm) are calculated to be 2.02 × 10−20cm2, and 2.50 × 10−20cm2 with the FWHM of 17.2 nm, and 10.5 nm, respectively. The fluorescence lifetime of 3P 0 has achieved great increasing by sensitizing of Yb3+ ion. Not only the up-conversion luminescence can be achieved, but also the broad band emission from 1D 2 energy level can be observed. The results show that Yb,Pr:CaF 2 could be a potential laser gain medium for visible and near-IR laser operation. • Not only the up-conversion luminescence can be achieved, but also the broad band emission from 1D 2 energy level can be observed by Yb3+ ion sensitizing. • Spectral properties and Judd-Ofelt parameters of Yb,Pr:CaF 2 crystal were investigated and analysed. [ABSTRACT FROM AUTHOR]

GdScO 3 single crystal codoped with Tm3+ and Tb3+ ions was successfully grown by the Edge-defined Film-fed Growth Method (EFG) for the first time. Absorption, fluorescence spectrum and fluorescence lifetimes of the grown crystal at room temperature were measured. The absorption cross-section at 789 nm was calculated to be 8.20 × 10−21 cm2. The emission cross-section was 1.35 × 10−21 cm2 at 1504 nm with the FWHM of 95.3 nm. The fluorescence lifetimes of the 3H 4 state and the 3F 4 state were fitted to be 253 μs and 1460 μs, respectively. Compared with Tm3+ single doped GdScO 3 crystal, the codoping of Tb3+ successfully depopulated the 3F 4 energy level and enhanced the emission at 1.5 μm region. It indicated that Tm,Tb:GdScO 3 could be favorable laser medium for 1.5 μm-laser operation. • Tm3+ and Tb3+ co-doped GdScO 3 crystal was successfully grown by the edge-defined film-fed method (EFG) for the first time. • Spectral parameters and Judd-Ofelt parameters of Tm,Tb:GdScO3 crystal were obtained and compared. • The fluorescence mechanism of Tm3+ and Tb3+ co-doped GdScO 3 crystal has been studied. [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]