INFRARED CROSS-SECTION MEASUREMENTS FOR CRYSTALS DOPED WITH ER3+, TM3+, AND HO3+

The absorption and emission cross sections of the transition between the ground spin-orbit multiplet and the lowest excited multiplet have been measured for the Er3+, TM3+, and Ho3+ ions in a variety of crystalline hosts. The materials that were investigated include LiYF4, Bay2F8, Y3Al5O12, LaF3, KCaF3, YAlO3, and La2Be2O5. The absolute magnitude of the emission cross sections were determined from the absorption spectra, with the aid of the principle of reciprocity. The calculated radiative emission lifetimes derived from these measured cross sections agree well with the actual measured emission decay times for most materials. The potential use of these rare-earth-doped materials in pulsed laser applications required that the ground state exhibit adequate splitting to minimize the detrimental effects of the ground state thermal population, and also that the emission cross section be sufficiently large to permit efficient extraction of energy. The systems based on Ho3+ in the eightfold coordinated sites of LiYF4, Bay2F8, and Y3Al5O12 appear to be most promising for this type of energy storage amplifier application.