Dynamics of the energy transfer in the Tm,Tb:LiYF/sub 4/ luminescent system

Summary form only given.The introduction of more than one kind of doping ions in laser materials has become quite usual. In all codoped materials, there exist interactions between pairs of dopants that drive nonradiative energy transfer processes creating additional channels of excitation or decay for the energy levels of interest, i.e., the laser levels. For Tm/sup 3+/ ions in fluoride crystals the 1.5-/spl mu/m emission (/sup 3/H/sub 4//spl rarr//sup 3/F/sub 4/) can be enhanced through such processes. The /sup 3/H/sub 4/ level can be directly pumped by high-power GaAlAs laser diodes around 800-nm, however, migration among Tm ions in that energy level and the self-quenching (/sup 3/H/sub 4/+/sup 3/H/sub 6//spl rarr//sup 3/F/sub 4/+/sup 3/F/sub 4/) of the fluorescence prevent high enough Tm concentration to ensure efficient pumping. Besides, the lifetime of the terminal level /sup 3/F/sub 4/ is longer than the /sup 3/H/sub 4/ emitting one, creating a detrimental bottlenecking effect.