Abstract

The thulium (Tm³⁺) doped solid state lasers, operating on the ³F₄→³H₆ transition are sources of broadly tunable “eye-safe” laser radiation in the 1.8 to 2.1 μm region. This spectral region is interesting for applications such as coherent radar systems, atmospheric remote sensing, high-resolution spectroscopy, and medical surgery. Fluoride crystals such as SrF₂ and CaF₂ are promising host material for Tm³⁺ ions with advantage of long radiative lifetimes, wide transparency, and low phonon energy. Codoping a matrix with similar but optically inactive RE³⁺ such as Gd³⁺ lead to a change in matrix local symmetry and thus a change in spectral and laser properties without a detrimental effect on the thermo-mechanical properties of the crystal [1,2,3]. In this paper we investigate the influence of temperature on absorption spectra and fluorescence lifetime of a new fluoride Tm,Gd:SrF₂ crystal [3]. The crystal was grown using the temperature gradient technique (TGT). The concentration of Tm³⁺ ions was 2 % and concentration of inactive Gd³⁺ ion was also 2 %.

© 2023 IEEE