Development of Cr(3+) elpasolites for tunable solid state lasers

Attempts to grow K2NaScF6 single crystals for near-IR Cr(3+) tunable lasers by vertical Bridgman methods have not been very successful, due to the presence of a deleterious crystal phase which forms when the proportions of starting materials correspond to formula stoichiometry. A mapping of the KF-ScF3-NaF ternary phase field has revealed that the formation of this minor phase can be suppressed through the use of an initial lean melt in KF and NaF. The radiationless relaxation of Cr(3+) fluorescence in Cs2NaYCl6 has also been theoretically and experimentally investigated, leading to results which demonstrate that linear coupling models are inadequate to explain the relaxation, and that quadratic coupling to a soft mode can account for it instead. Parameters are given for a broadband GSGG:Cr(3+) laser operated under pulsed excitation.