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A new laser crystal from Lu2.4Y0.6Al5O12 (LuYAG) co-doped with Cr3+, Tm3+, Ho3+, and Pr3+ ions was grown successfully by the Czochralski method for the first time. The structure parameters of the Cr,Tm,Ho,Pr:LuYAG crystal are determined by the X-ray Rietveld refinement method. The main absorption bands are observed near 426 and 782 nm, and the fluorescence spectrum excited by a 450 nm or 783 nm LD presents an emission band near 2.911 μm, indicating that the co-doped Cr3+ and Tm3+ ions can be utilized as sensitizers for the Ho3+ ions. The lifetimes of the 5I6 and 5I7 levels of the Ho3+ ions were measured and fitted to be 0.070 ms and 1.852 ms, respectively. The energy transfer efficiencies of the processes 5I6 (Ho3+) →3F3,4 (Pr3+) and 5I7 (Ho3+) →3F2 (Pr3+) + 3H6 (Pr3+) were calculated, showing that the Pr3+ ions can play the role of a deactivator for the Ho3+ ions. Furthermore, the energy transfer mechanisms among the Cr3+, Tm3+, Ho3+, and Pr3+ ions were studied. The results suggest that the Cr,Tm,Ho,Pr:LuYAG crystal is a new promising laser medium operating at around 2.9 μm under flash lamp or 783 nm LD pumping. [ABSTRACT FROM AUTHOR]

Single crystals of Dy:GdScO3 and Dy,Tb:GdScO3 have been successfully grown by the Czochralski method. High crystalline quality of both crystals was determined via X-ray rocking curves. Effective segregation coefficients of Dy3+ and Tb3+ ions in GdScO3 host were calculated to be ∼0.7 and 1.03, respectively. The large FWHMs and absorption cross-sections of Dy:GdScO3 and Dy,Tb:GdScO3 crystals at 452 nm indicate that they can be efficiently pumped by the commercial blue GaN laser diodes. Both Dy:GdScO3 and Dy,Tb:GdScO3 exhibit relatively large stimulated emission cross-sections at 578 nm and relatively long fluorescence lifetimes. In particular, Dy,Tb:GdScO3 shows an enhanced yellow emission at around 578 nm. The energy transfer between Dy3+ and Tb3+ ions is beneficial for realizing population inversion by depopulating the population of the lower laser level of Dy3+ and has negligible influence on the upper laser level. Additionally, the defects and thermal properties of Dy:GdScO3 were investigated since they are very important for crystal growth and laser applications. Collectively, these results suggest that Dy:GdScO3 and Dy,Tb:GdScO3 can be regarded as promising candidates for realizing 578 nm laser output. [ABSTRACT FROM AUTHOR]