SPECTRAL PROPERTIES OF THE Cr 3+ DOPED Ca 3Al 2Ge 3O 12 GARNETS

The spectral properties of Cr 3+ doped calcium aluminium germanate garnet (Ca 3Al 2Ge 3O 12 ) have been investigated. Dependence of the zero phonon line positions from Cr 3+ in the inequivalent crystallographic sites has been studied as a function of concentration and temperature. The crystal field intensity parameters D q and Racah parameters were deviated by analyzing the absorption and emission spectra. The fine structure of Cr 3+ in Ca 3Al 2Ge 3O 12 at low temperature has been assigned as a vibronic progression in two kinds of phonon with energies ω 1(A)=165～170cm -1 , ω 2(A)=200cm -1 and ω 1(B)=130～135cm -1 , ω 2(B)=185～190cm -1 . The luminescence decay behavior of Cr 3+ different transitions has been investigated upon red laser excitation and showing single exponential decay curves.