A YAG crystal exhibiting high phonon energy is used as the doping matrix to accelerate the depopulation of the ⁶H_13/2 energy level by multi-phonon relaxation and improve the population inversion velocities of the laser upper and lower energy levels. Simultaneously, an energy transfer between Dy ³⁺∶ ⁶H_13/2 and Tb ³⁺∶ ⁷F₄ is achieved by introducing Tb ³⁺ ions exhibiting an energy level similar to that exhibited by the laser lower level; thus, the energy lifetime of ⁶H_13/2 is successfully reduced and the yellow laser output of 582.1 nm is obtained for the very first time. Furthermore, the effects of the Tb ³⁺ ions on the lifetime of the laser upper energy levels are analyzed by comparing the Dy:YAG and Dy-Tb:YAG fluorescence spectra.