2　at.%　Dy3+:　BaF2　and　2　at.%　Dy3+/2　at.%　RE3+(RE3+　=　Gd3+,　Y3+,　Lu3+):　BaF2　single　crystals　were　grown　by　the　Bridgman-Stockbarger　method,　and　characterized　by　absorption,　visible　emission,　and　fluorescence　decay　curves.　Also,　relying　on　the　excitation　and　emission　spectra,　decay　curves　at　low　temperature　(77　K)　for　Dy3+:　BaF2　and　Dy3+/RE3+(RE3+　=　Gd3+,　Y3+,　Lu3+):　BaF2　crystals　have　been　measured.　We　found　that　Dy　ions　have　at　least　three　lattice　sites　in　BaF2　crystal,　and　the　lattice　sites　of　Dy3+　ions　can　be　reduced　by　co-doping　with　Gd3+,　Y3+　or　Lu3+　ions,　where　Dy3+:　BaF2　and　Dy3+/RE3+(RE3+　=　Gd3+,　Y3+,　Lu3+):　BaF2　single　crystals　can　be　considered　as　quasi-single　lattice　crystals.　From　visible　fluorescence　spectra,　it　was　found　that　co-doping　Gd3+　will　increase　the　emission　intensity　of　yellow　light　by　20　times,　co-doping　Y3+　will　increase　the　emission　intensity　of　yellow　light　by　30　times,　and　co-doping　Lu3+　will　increase　the　emission　intensity　of　yellow　light　by　25　times.　The　calculated　absorption　cross-section,　emission　cross-section,　and　fluorescence　lifetimes　indicate　that　Dy3+:　BaF2　and　Dy3+/RE3+(RE3+　=　Gd3+,　Y3+,　Lu3+):　BaF2　crystals　especially,　Dy3+/Y3+:　BaF2　crystals　are　suitable　to　achieve　yellow　laser　output.　©　2022