Photoluminescence spectra were measured under different excitation wavelengths.The co-doped samples show enhanced Sm3 ions emission at the cost of Ce3 emission with the increasing Ce3 ions concentration which shows that Ce3 is acting as a sensitizer.This kind of luminescent behavior is discussed with respect to energy transfer process.The investigation based on excitation spectra and decay curves demonstrated that the energy transfer is non radiative in nature taking place between Ce3 and Sm3 clusters.It is governed by dipole – dipole interactions as explained in terms of donor lifetime.