TEMPERATURE-DEPENDENCE OF SPECTRAL LINEWIDTHS AND LINESHIFTS OF ND3+ IONS IN CAY2MG2GE3O12 LASER CRYSTAL

We have investigated the widths and shifts of the luminescence F-4(3/2 )-->I-4(9/2) line at 940 nm (R(1)-->Z(5)) and of the F-4(3/2)-->I-4(11 /2) line at 1046 nm (R(2)-->Y-1) in the laser crystal CaY2Mg2Ge3O12:Nd 3+,Cr3+ from 78 to 300 K. The linewidths are over 20 cm(-1). The R(2)- ->Y-1 line position was found to shift to a longer wavelength and the R(1)-->Z(5) to a shorter wavelength with increasing temperature. The r esults on the thermal line broadening and shifts are compared with the existing theory which uses a simplified ion-phonon interaction as a p erturbation and assumes a Debye phonon distribution for the solid.