Laser spectroscopic studies of Tb³⁺-doped oxyfluoroborate glass

Tb³⁺-doped oxyfluoroborate glasses have been prepared for different concentrations of Tb. The absorption, fluorescence and photoacoustic spectra of these have been recorded and studied. It is marked that the fluorescence intensity of different fluorescence transitions decreases with the increase of Tb ion concentration in the glass. This quenching at higher concentration is due to the energy transfer among the excited and nearest neighbor unexcited Tb ions in the glass. The lifetime measurement confirms it, as the lifetime of a particular state was found to decrease with the increase of Tb ion concentration in the glass. The mechanism of the energy transfer process was determined to involve quadrupole-quadrupole interaction. We have also studied the energy transfer from Tb³⁺→Pr³⁺ when both the rare earths are doped together in the glass. A decrease in the lifetime of the ⁵D₄ level of Tb³⁺ with the increase of Pr³⁺ concentration confirms this.