Spectroscopic properties of Ho 3+ ions in biaxial Lu 2SiO 5 crystal

Abstract

A high optical quality Ho 3+-doped lutetium orthosilicate laser crystal Lu 2SiO 5 has been grown by the Czochraski method and the accurate concentration of Ho 3+ ions in the crystal was measured. The polarized absorption spectra, polarized fluorescence spectra and fluorescence decay curve of Ho 3+ ions in the Lu 2SiO 5 crystal were measured at room temperature. Based on the Judd–Ofelt model, three effective intensity parameters were determined as: Ω 2 , eff = 4.57 × 10 −20 cm 2, Ω 4 , eff = 3.11 × 10 −20 cm 2, Ω 6 , eff = 1.42 × 10 −20 cm 2. The fluorescence lifetime of the 5 I 7 manifold for Ho 3+ ions was measured to be 3.3 ms and the quantum efficiency was estimated. The polarized emission cross-sections for the 5 I 7 → 5 I 8 transition were determined by Fuchtbauer–Ladenburg formula. The good spectroscopic properties imply that Ho: Lu 2SiO 5 crystal is a potential laser gain medium for 2 μm lasers.