Growth and spectral properties of Yb³⁺/Ho³⁺ co-doped NaGd(MoO₄)₂ crystal

A Yb³⁺/Ho³⁺ co-doped NaGd(MoO₄)₂ crystal was successfully grown by the Czochralski method. The crystal structure and lattice parameters were determined by the powder X-ray diffraction method. The absorption and fluorescence spectra of the crystal were investigated at room temperature. The refractive index of NaGd(MoO₄)₂ crystal was calculated according to the infrared-corrected Sellmeier equation. Based on the Judd-Ofelt theory, the intensity parameters Ω _t (t = 2, 4, 6) of Ho³⁺ were derived. The spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes of the main multiplets of Ho³⁺ ion were calculated as well. The stimulated emission cross section for the transition from ⁵ I ₇ to ⁵ I ₈ of Ho³⁺ was calculated to be 1.2320 × 10^–20 cm^–2 by the Füchtbauer-Ladenburg equation with the full width at half maximum of 117.8 nm.