Strong Photoluminescence Through Up and Down Conversion in Tm3+/Ho3+:LaOF Nanoparticles

Efficient up and down frequency conversions in Tm3+ and Ho3+ doped LaOF tetragonal nanocrystals have been investigated. Bright fluorescence emissions are obtained in co-doped Tm3+/Ho3+:LaOF tetragonal nanocrystals through UV and infrared excitation. Green florescence from doped Ho3+ ions, which can be clearly seen with bared eyes, is obtained when Tm3+ ion is excited. Specific mechanism of the cross relaxation between doped ions is explored through spectroscopic measurements in time and frequency domains. About 90% energy transfer efficiency is obtained when the weak radiative and nonradiative relaxations are neglected.