Energy transfer and frequency upconversion involving triads of Pr3+ ions in (Pr3+, Gd3+) doped fluoroindate glass

Abstract

Blue and ultraviolet luminescence in (${\mathrm{Pr}}^{3+}$ , ${\mathrm{Gd}}^{3+}$ ) doped fluoroindate glass is studied for excitation in the red region $(\approx 590\mathrm{nm})$ . Frequency upconversion (UC) is observed due to energy transfer (ET) among three ${\mathrm{Pr}}^{3+}$ ions initially excited to the ${}^{1}D_2$ state corresponding to the ET process ${}^{1}D_2+{}^{1}D_2+{}^{1}D_2\to {}^{1}S_0+{}^{3}H_5+{}^{3}H_5$ . Additionally, UC luminescence from states ${}^{6}P_{7∕2}$ and ${}^{6}I_{7∕2}$ of ${\mathrm{Gd}}^{3+}$ is observed for an excitation wavelength resonant with transitions of the ${\mathrm{Pr}}^{3+}$ ions. The characterization of the luminescence signals allowed to determine ET rate among the ${\mathrm{Pr}}^{3+}$ ions and provides evidence of interconfigurational ET between ${\mathrm{Gd}}^{3+}$ and ${\mathrm{Pr}}^{3+}$ ions.