The temperature dependence of Cr3+:YAG zero-phonon lines

This paper deals with the photoluminescence temperature dependence of the zero-phonon lines of Cr(3+) ions in an yttrium aluminium garnet (YAG) matrix. Experimental data were analysed in the framework of electron-phonon coupling in the quadratic approximation and it was found that Cr(3+) ions in the YAG matrix are strongly coupled with lattice vibrations, with a Debye temperature of about 550 K and a value of the quadratic coupling constant of 0.65. The analysis of both homogeneous and inhomogeneous contributions to the photoluminescence linewidth is performed and the results obtained are compared with previously reported data for Fe(3+):YAG and discussed with respect to the different dependences of the two transition metal ions on the crystal field.