Spectroscopic observations were made on Lu:Nd:YAG and Nd:YAG laser materials. Variations in the UV absorption strengths are described and related to the presence of Lu
3+. These results indicate that an optimum Lu/Nd ion ratio exists that will yield minimum absorption by the host over the wavelength range

m. The reduction in absorption will minimize nonuniform heating effects that should lead to better laser performance under certain conditions.