Growth and optical properties of Ho3+:NaGd(MoO4)2 crystal

Abstract

Abstract The Ho 3+ :NaGd(MoO 4 ) 2 crystal with dimensions of Ф12 × 42 mm 2 has been grown by Czochralski (CZ) method. Polarized absorption and fluorescence spectra at room temperature were investigated. The largest absorption cross-sections, corresponding to 5 I 8 → 5 G 6 + 5 F 1 absorption bands, are 31.0 × 10 −20 cm 2 and 23.8 × 10 −20 cm 2 for π- and σ-polarization, respectively. The strongest emission corresponding to the 5 S 2 + 5 F 4 → 5 I 8 transition can be induced by populating any higher energy level of Ho 3+ ion. The fluorescence lifetimes at room temperature are 3.4 μs at 550 nm, 3.5 μs at 754 nm and 46.4 μs at 1193 nm, corresponding to transitions 5 S 2 + 5 F 4 → 5 I 8 , 5 S 2 + 5 F 4 → 5 I 7 , 5 I 4 → 5 I 8 , and 5 I 6 → 5 I 8 , respectively. Due to the influence of fluorescence trapping, the measured fluorescence lifetimes of 550 and 1193 nm should be longer than their actual values. Based on the Judd–Ofelt (J–O) theory and polarized absorption spectrum, the spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes were calculated.