Growth and investigation of optical properties and laser oscillations from ternary thiogallate crystals with laser active dopants

A wide range of rare earth doped crystals used as a lasing media includes: Y3Al5O12 (YAG); Al2O3 (sapphire); chalcogenides of ZnS, ZnSe; sesquioxides of Y2O3, Sc2O3 and others. Ternary thiogallate compounds with common formula AIIB23C4 6 (where A is: Ca, Sr, Ba; B is: Ga, Al; C is- S, Se, Te) consider as a perspective class of chalcogenide semiconductors revealing bright luminescence and laser oscillation properties when doped with rare-earth elements (Eu2+, Nd3+ , Ce3+ etc). In the present research, optical properties and observed laser oscillation of transparent ternary chalcogenide crystals of CaGa2S4 and CaGa2Se4 grown by the chemical vapor transport reaction and doped with Eu2+ (1.0-5.0 a t%) are described. The first observation of laser oscillation from a single crystal CaGa2S4 : Eu2+ (1.0-5.0 at%) have been reported earlier, and for CaGa2Se4 : Eu2+ it is reported for the first time in the present article. The life time of the excited state 4f65d of Eu2+ ions in both crystals determined from the luminescence decay kinetics was ~3.8 μsec. It is shown that photoluminescence maximum in both crystals CaGa2S4 : Eu2+ and CaGa2Se4 : Eu2+ is due to the intra shell transition 4f65d – 4f7(8S7/2) ions.