부산대학교 도서관

The thulium $(\text{Tm}^{3+})$ doped solid state lasers, operating on the $3\mathrm{F}_{4}\Rightarrow^{3}\mathrm{H}_{6}$ transition are sources of broadly tunable “eye-safe” laser radiation in the 1.8 to 2.1 $\mu \mathrm{m}$ 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 $\text{SrF}_{2}$ and $\text{CaF}_{2}$ are promising host material for $\text{Tm}^{3+}$ ions with advantage of long radiative lifetimes, wide transparency, and low phonon energy. Codoping a matrix with similar but optically inactive $\text{RE}^{3+}$ such as $\text{Gd}^{3+}$ 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]–[3]. In this paper we investigate the influence of temperature on absorption spectra and fluorescence lifetime of a new fluoride Tm,Gd: $\text{SrF}_{2}$ crystal [3]. The crystal was grown using the temperature gradient technique (TGT). The concentration of $\text{Tm}^{3+}$ ions was 2 % and concentration of inactive $\text{Gd}^{3+}$ ion was also 2 %.