Fluorescence lifetime and quantum efficiency for 5d → 4f transitions in Eu2+ doped chloride and fluoride crystals

Abstract An investigation of the relevant parameters for broadly tunable lasers utilizing the efficient, broad-band 5d → 4f emission in a number of Eu2+ doped metal fluorides, chlorides, and fluoro-chlorides has been performed. Results of measurements of absorption and emission spectra, quantum efficiencies, and fluorescence lifetimes in MF2 and MCl2 (M = Ca, Ba, Sr) and MFCl (M = Ba, Sr) are presented. A calculation of the pump energy threshold for laser action in CaF2 : Eu2+ based on our spectroscopic data is made. Although the estimation indicated that laser threshold in CaF2 : Eu can be easily achieved, strong excited-state absorption in this system was found to prohibit laser oscillation.