Abstract

${\mathrm{Na}}_5{\mathrm{Lu}}_9{\mathrm{F}}_{32}$ single crystals co-doped with 1 mol. % ${\mathrm{Er}}^{3+}$ and various concentrations (0.1 mol. %, 0.3 mol. %, 0.5 mol. %, 0.7 mol. %, and 1 mol. %) of ${\mathrm{Pr}}^{3+}$ were successfully grown using the Bridgman method. Optical spectroscopic investigations of the obtained single crystal were reported for the absorption, emission, and luminous decay. The obtained single crystal appears with almost no absorption at the 2.7 μm band, attributable to the ${\mathrm{OH}}^{-}$ bond. According to the Judd–Ofelt (J-O) theory, the J-O intense parameters of ${\mathrm{Er}}^{3+}$ ions were calculated. Under the 980 nm LD pumping, an obviously enhanced emission at 2.7 μm was obtained in the ${\mathrm{Er}}^{3+}/{\mathrm{Pr}}^{3+}$ co-doped crystal compared with the ${\mathrm{Er}}^{3+}$ singly doped crystal due to the energy transfer from ${\mathrm{Er}}^{3+}$ to ${\mathrm{Pr}}^{3+}$. The most intense emission at 2.7 μm was obtained when the doping concentrations of ${\mathrm{Er}}^{3+}$ and ${\mathrm{Pr}}^{3+}$ were 1 mol. % and 0.5 mol. % in the present research. The maximum emission cross-section and gain cross-section at 2.7 μm were also estimated. Moreover, using the Dexter theory, the energy transfer microscopic parameters have been calculated, and the decay curve fitting using the Inokuti–Hirayama expression indicated the dipole–dipole energy transfer from ${\mathrm{Er}}^{3+}$ to ${\mathrm{Pr}}^{3+}$ ions.

© 2017 Optical Society of America