Frequency upconversion of orange light into blue light inPr3+-doped fluoroindate glasses

Excitation of the transition ${}_{}{}^3{}_{}{}^{}$ ${\mathit{H}}_4$ ${\to }^1$ ${\mathit{D}}_2$ in a ${\mathrm{Pr}}^{3+}$-doped fluoroindate glass at ∼588 nm results in efficient blue emission at ∼480 nm which is ascribed to the ${}_{}{}^3{}_{}{}^{}$ ${\mathit{P}}_0$ ${\to }^3$ ${\mathit{H}}_4$. The upconversion process is due to an energy transfer involving a pair of ${\mathrm{Pr}}^{3+}$ ions. The dynamical behavior of the anti-Stokes emission is described using a rate-equation model which allows one to obtain the energy-transfer rates involving the pair states which contribute to the upconversion process.