We grew several thulium- (Tm-) doped La<sub>2</sub>Be<sub>2</sub>O<sub>5</sub> crystals and determined the concentration of the incorporated Tm using proton-induced x-ray emission. Polarized absorption and emission spectra of Tm:La<sub>2</sub>Be<sub>2</sub>O<sub>5</sub> were investigated, allowing the stimulated-emission cross section to be estimated with the reciprocity method and the Fuchtbauer–Ladenburg equation. We report lifetime measurements of each of the transitions from the <sup>3</sup>F<sub>4</sub> to <sup>3</sup>H<sub>6</sub> multiplet and relate them to the radiative lifetime. In view of these results we revisit the question of Tm:La<sub>2</sub>Be<sub>2</sub>O<sub>5</sub> as a prospective laser material for laser emission at 1.8 μm in the presence of losses and determine the pumping threshold and slope efficiency for a typical resonator geometry.
© 1998 Optical Society of America
Vikas Sudesh, J. A. Piper, E. M. Goldys, and R. S. Seymour, "Growth, characterization, and laser potential of Tm:La2Be2O5," J. Opt. Soc. Am. B 15, 239-246 (1998)