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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]

Yb:CaYAlO 4 (Yb:CALYO) shaped crystal fibers with different Yb3+ doping concentration were successfully grown by the micro-pulling-down (μ -PD) method. The effect of the Yb3+ concentration on the structure, absorption, emission and lifetime was systematically studied. The strongest absorption peaks of Yb:CALYO crystal fibers are located at 977 nm for σ and π polarization. The micro-photoluminescence indicate that Yb3+ ions in CALYO single crystal fiber grown by the μ -PD method distributed evenly across a cross-section. The emission cross-section of 5 at.% Yb:CALYO crystal fiber was calculated to be 0.86 × 10−20 and 1.08 × 10−20 cm2 at 983 nm for σ and π polarizations. Benefited from the disordered structrure of CaYAlO 4 crystal, the full width at half maximum (FWHM) at 978 nm was 68.9 nm and 80.9 nm, respectively. The fluorescence lifetime of 2F 5/2 energy level of Yb:CALYO crystal fibers with concentration of 0.5 at.%, 1 at.%, 2 at.% and 5 at.% was calculated to be 435 μs, 484 μs, 514 μs and 453 μs, respectively. The experimental results show that Yb:CALYO crystal fiber is a potential laser medium for ultrashort laser operation. • Yb:CaYAlO 4 shaped crystal fibers were grown by the micro-pulling down method. • The crystal structure, polarized spectra were investigated. • The effect of Yb3+ concentration on the spectroscopic properties was evaluated. [ABSTRACT FROM AUTHOR]