We have investigated the structural and optical properties of rare earth-doped zinc tellurite glasses modified by the substitution ofZnF2.Raman and phonon sideband spectroscopies were employed to characterize changes in the glass structure as well as to probe vibrational behavior in the immediate vicinity of the rare earth ion. These measurements are combined with photoluminescence and optical absorption to monitor the effect of halide substitution upon the optical behavior of the rare earth dopant. A substantial increase in the intrinsic radiative lifetime ofNd3+is observed with increasing halide concentration. ©1997 American Institute of Physics.