Spectral-Linewidth Studies ofPr3+in Yttrium Aluminum Garnet

It has been recently shown that the variation of spectral linewidth as a function of temperature in sharp optical spectra can be adequately explained in terms of phonon-ion interactions. A detailed analysis of the ${}_{}{}^3{}_{}{}^{}H_4^{}{}_{}{}^{}\to {}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ transitions of ${\mathrm{Pr}}^{3+}$ (1%) in yttrium aluminum garnet (YAG) has allowed the analysis of the resultant line-broadening effect into its component ion-relaxation processes, each having its own temperature variation. Our results show that it is necessary to include the temperature-dependent direct phonon processes, if agreement is to be reached between the theoretical expression for the linewidth and the experimental data. In many previous studies these processes had been included only as a constant factor, independent of temperature. The coupling parameters for these transitions have been determined and are consistent with the nature of the YAG lattice.