Optical high-resolution spectroscopic study of Tm3+ crystal-field levels in LiLuF4

We report on the first high-resolution study of LiLuF4:Tm3+. The accurate energy level scheme of Tm3+ in the LiLuF4 matrix was obtained for the 3H6,5,4, 3F4,3,2, and 1G4 multiplets. It was shown that electric-dipole transitions dominate for all the studied multiplets except the 3H5 one.