Enhanced 2.8 μm emission of Ho,Pr:CaYAlO4 crystal

Ho,Pr:CaYAlO4 (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+:5I7 to Pr3+:3F2 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 5I6 and 5I7 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.