THE GROWTH AND OPTICAL ASSESSMENT OF CR3-DOPED RX(BO3)(4) CRYSTALS WITH R=Y,GD - X=AL,SC()

This paper reports the high temperature top-seeded solution growth (TS SG) of Cr3+-doped mixed berate crystals having the general formula RX( 3)(BO3)(4), with R(3+), Y3+ or Gd3+ and X(3+) = Al3+ or Sc3+. Both YAl 3(BO3)(4) (YAB) and CdAl3(BO3)(4) (GAB) have been grown from a mixed K 2Mo3O10-B2O3 flux, whereas YSc3(BO3)(4) (YSB) and GdSc3(BO3)(4) (GSB) are grown from K2Mo3O10-Li2B4O7 mixtures. Typical crystals ranging in volume from 60 mm(3) to 14 cm(3) have been grown, with Cr3+ concentrat ions of order 0.2-5.0 at%. Measurements of the optical absorption and luminescence spectra show that in YAI(3)(BO3)(4) and GdAl3(BO3)(4) the Cr3+ ions occupy strong crystal field sites whereas in YSc3(BO3)(4) a nd GdSc,(BO,), these ions occupy weak field sites. The significance of this observation is that the Cr3+ ions in weak field sites emit via t he broadband T-4(2) --> (4)A(2) transitions, with obvious potential as tunable laser gain media.