INFRARED (ER)BAY2F8 LASER PUMPED THROUGH DI-IONIC AND TRI-IONIC UPCONVERSION PROCESSES

Emission and absorption spectra of (5% Er) BaY2F8 were studied at 300, 77, and 4.2 °K. Stark-level positions were determined from the liquid-helium absorption spectra. Emission spectra were excited with a UV flash lamp and 1.53-μm radiation from an Er:glass laser; in the latter case, the visible and near-IR fluorescence of the Er3+ ions was excited through a multiphoton upconversion process. The lifetimes of Er3+-ion-excited states were measured at 300 and 77 °K. Laser action was stimulated at 0.85, 1.73, and 2.796 μm in a (5% Er) BaY2F8 laser rod using the transitions 4S 3/2→4IJ, where J=13/2, 9/2, and 4I11/ 2→4I13/ 2, respectively. A Xe flash lamp was used for optical pumping. The latter two laser transitions were also pumped through upconversion of 1.53-μm radiation of the Er:glass laser. The cross-relaxation ion-pair conversion coefficient for the 4I13/ 2 levels of the Er3+ ions in BaY 2F8 was calculated to be α=3.7×10 -17 cm-3 s -1.