COMPOSITIONAL DEPENDENCE OF INFRARED-TO-VISIBLE UP-CONVERSION IN YB3-CODOPED AND ER3+-CODOPED GERMANATE, GALLATE, AND TELLURITE CLASSES()

Upconversion fluorescences of the green S-4(3/2) --> I-4(15/2) and red F-4(9/2) --> I-4(15/2) transitions of the Er3+ ion are studied for Yb 3+ - and Er3+-codoped sodium germanate, potassium tantalum gallate, an d barium tellurite glasses by InGaAs laser-diode pumping. The phonon e nergies of the host glasses are determined by infrared-reflection meas urements. Compositional effects on the Jud-Ofelt parameters for the Er 3+ ion, the spontaneous emission probability (SPE) of the F-2(5/2) --> F-2(7/2) transition for the Yb3+ ion, and the phonon energy of the gl ass network are discussed in terms of glass structure. The factors tha t affect the upconversion fluorescence intensities of the Er3+ ion are discussed, using the phonon energy of the host glass and the SPE for the Yb3+ ion in the germanate, gallate, and tellurite glasses.