Excited-state absorption in Eu+2: CaF2 and Ce+3: YAG single crystals at 298 and 77 K

Abstract

Excited-state absorption has been studied in Eu+2-doped CaF2 and in Ce+3-doped Y3Al5O12 at room temperature and 77 K. It is shown that the conduction band of the host crystal is responsible for absorption in both systems. In Eu+2: CaF2 the excited-state absorption is caused by a transition from the fluorescence level, the 4f6(7F)5d(2eg)G8 state, to the conduction band of CaF2. In Ce+3: YAG two processes are responsible for the absorption: (1) excitation from the lowest Ce+3 5d energy level to the conduction band of YAG and (2) transitions from the ground state of a trap to its excited states and to the conduction band of YAG. The results provide general guidelines in the search for new uv solid-state laser materials.