Compositional Dependence of Infrared‐to‐Visible Upconversion in Yb 3+ ‐ and Er 3+ ‐Codoped Germanate, Gallate, and Tellurite Glasses

Upconversion fluorescences of the green 4 S 3/2 → 4 I 15/2 and red 4 F 9/2 → 4 I 15/2 transitions of the Er 3+ ion are studied for Yb 3+ ‐ and Er 3+ ‐codoped sodium germanate, potassium tantalum gallate, and barium tellurite glasses by InGaAs laser‐diode pumping. The phonon energies of the host glasses are determined by infrared‐reflection measurements. Compositional effects on the Judd—;Ofelt parameters for the Er 3+ ion, the spontaneous emission probability (SPE) of the 2 F 5/2 → 2 F 7/2 transition for the Yb 3+ ion, and the phonon energy of the glass network are discussed in terms of glass structure. The factors that affect the upconversion fluorescence intensities of the Er 3+ ion are discussed, using the phonon energy of the host glass and the SPE for the Yb 3+ ion in the germanate, gallate, and tellurite glasses.