Temperature dependence of spectral linewidths and lineshifts of Nd3+ ions in CaY2Mg2Ge3O12 laser crystal

We have investigated the widths and shifts of the luminescence 4F3/2→4I9/2 line at 940 nm (R1→Z5) and of the 4F3/2→4I11/2 line at 1046 nm (R2→Y1) in the laser crystal CaY2Mg2Ge3O12:Nd3+,Cr3+ from 78 to 300 K. The linewidths are over 20 cm−1. The R2→Y1 line position was found to shift to a longer wavelength and the R1→Z5 to a shorter wavelength with increasing temperature. The results on the thermal line broadening and shifts are compared with the existing theory which uses a simplified ion-phonon interaction as a perturbation and assumes a Debye phonon distribution for the solid.