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Ho,Pr:CaYAlO 4 (Ho,Pr:CYA) crystal doped with 1 at.% Ho3+ and 0.1 at.% Pr3+ was successfully grown using the Czochralski method. Polarized absorption spectra, emission spectra, and fluorescence lifetime measurements were performed. The impact of Pr3+ co-doping on the ∼3 μm emission of Ho3+ ions was analyzed. The energy transfer efficiency from Ho3+:5I 7 to Pr3+:3F 2 energy level was calculated to be 60.66 %, indicating that Pr3+ effectively mitigated the self-termination effect in Ho,Pr:CYA crystals. The absorption cross-section at 645 nm was found to be 1.53 × 10−20 cm2 for σ polarization and 2.62 × 10−20 cm2 for π polarization. The emission cross-section at 2842 nm was calculated to be 0.86 × 10−20 cm2 for σ polarization and 1.33 × 10−20 cm2 for π polarization at 2908 nm, with a full width at half maximum (FWHM) of 139 nm and 88 nm, respectively. The fluorescence lifetimes of the 5I 6 and 5I 7 levels were measured to be 0.17 ms and 2.01 ms, respectively. These results collectively suggest that Ho,Pr:CYA crystals hold great potential as a candidate for 2.8 μm laser applications. • Ho3+,Pr3+ co-doped CaYAlO 4 crystal was grown by the Czochralski method. • The crystal structure, polarized absorption and emission spectra were investigated. • The intensity parameters were obtained using J-O theory. [ABSTRACT FROM AUTHOR]

Ho3+ and Eu3+ co-doping GdScO 3 crystal was successfully grown by special EFG method. The spectroscopic properties of the crystal were measured and analyzed. The absorption cross section was calculated to be 2.027 × 10−20 cm2 at 1161 nm. The J-O theory intensity parameters Ω t (t = 2, 4, 6), radiative transition rates, fluorescence branching ratios and radiative lifetimes were calculated. The Ho,Eu:GdScO 3 crystal has very strong emission at 2869 nm and the emission cross section was 13.524 × 10−21 cm2. The fluorescence lifetimes of the 5I 7 and 5I 6 levels were measured to be 4.457 ms and 1.265 ms. Confirmed that Eu3+ can be used as an effective deactivation ion of Ho3+ in GdScO 3 crystal. All those results show that the Ho,Eu:GdScO 3 crystal would be a potential laser material for ∼3 μm mid-infrared region. • Ho,Eu:GdScO 3 crystal was successfully grown. • The spectroscopic properties of the Ho,Eu:GdScO 3 crystal were analyzed. • J-O theory was applied to analyze fluorescence properties of the Ho,Eu:GdScO 3 crystal. • The energy transfer between Ho3+ and Eu3+ ions, spectroscopic characteristic of ∼3 μm emission were calculated and analyzed. [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]

Ho:Lu 2 O 3 crystal was successfully grown by TGT method. The spectroscopic properties of the crystal were analyzed. The absorption cross section of Ho:Lu 2 O 3 were 0.307 × 10−20 cm2 at 1147 nm and 1.076 × 10−20 cm2 at 1929 nm. J-O theory was applied to analyze fluorescence properties of the Ho:Lu 2 O 3 crystal. The intensity parameters Ω t (t = 2,4,6), radiative transition rates, branching ratios and radiative lifetime were calculated. The Ho:Lu 2 O 3 crystal had very strong emission at 2027 nm and 2849 nm and emission cross sections were calculated to be 3.271 × 10−21 cm2 and 8.852 × 10−21 cm2, respectively. The fluorescence lifetimes of the Ho3+5I 7 and 5I 6 levels were measured to be 12.400 ms and 0.622 ms. All those results show that the Ho: Lu 2 O 3 crystal would be a potential laser material for mid-infrared region. • Ho: Lu 2 O 3 crystal was successfully grown by TGT method. • The spectroscopic properties of the Ho: Lu 2 O 3 crystal were analyzed. • J-O theory was applied to analyze fluorescence properties of the Ho:Lu 2 O 3 crystal. • The gain cross-section of Ho:Lu 2 O 3 crystal for ∼2 μm region and ∼3 μm region were calculated. [ABSTRACT FROM AUTHOR]