Optical properties of Dy3+-doped CaYAlO4 crystal

Optical spectroscopic properties of Dy3+ ions in Dy:CaYAlO4 single crystals were investigated, aiming at evaluating the potential for visible laser applications. The crystals were grown by the Czochralski technique in reducing atmosphere in order to circumvent the color-center formation in this host material. Chemical compositions of the as-grown crystals were determined by electron probe micro-analysis. Absorption and emission spectra were recorded in the visible and near infrared spectral range at room temperature. Experimental oscillator strengths derived from the ground-state absorption transitions were used to fit the electrostatic, spin-orbit coupling as well as Judd-Ofelt intensity parameters. The theoretical electric dipole as well as magnetic dipole oscillator strengths, fluorescence branching ratios, and radiative lifetime were calculated in the framework of Judd-Ofelt theory. Experimental and calculated results showed that the yellow 4F9/2→6H13/2 transition features the largest branching ratio and emission cross-sections under 453-nm excitation. Fluorescence decay profiles were recorded to analyze the fluorescence lifetime of the 4F9/2 level. Anisotropy of magnetic-dipole transitions was observed in the spectroscopic study and discussed in detail.