Sm³⁺ ions, respectively, in the co-doped glasses. The intensity of green and orange emission lines of co-doped glasses mixed with 8.0 mol% of Pb₃O₄ seemed to have been intensified nearly two times when compared with that of Sm³⁺ individually doped glasses. The increased efficiency of these two emissions is attributed to the decreasing covalent character of glass network due to the increasing concentration of Pb₃O₄ and the mutual energy transfer between the two co-dopant ions. The emission process is further analyzed using rate kinetic equations and the resultant emission intensities are found to be proportional to the life time of the corresponding excited state.