Full Length ArticleSpectroscopic properties of Tm3+ optical centers at the 3F4-3H6 2-μm laser transition in BaF2 crystal

Individual low temperature (77 K) fluorescence spectra of clustered and new long-lifetime optical centers of Tm3+ ions at the 3F4-3H6 transition are separated and the lifetimes of these centers are measured. Analysis of the positions of the fluorescence lines of the newly observed optical center at the 3F4-3H6 and 1G4-3H5 transitions allows us to suggest that it has a tetragonal (C4v) local symmetry.