Direct nanosecond Nd→Ce nonradiative energy transfer in cerium trifluoride laser crystals

Using third harmonics of LiF:F2+ tunable color center laser excitation and selective fluorescence detection the temperature and concentration dependencies of fluorescence decay curves of the high-lying 4D3/2 manifold of the Nd3+ ion were measured in CeF3 crystals. As a result the temperature dependence of energy transfer kinetics from the 4D3/2 manifold of the Nd3+ donor ions to the 2F7/2 manifold of the acceptor Ce3+ ions in the ordered practically 100% filled CeF3:Nd3+ (0.056 wt%) crystal lattice was determined for 13–55 K. Based on the temperature dependence the mechanisms and the channels of the Nd→Ce nonradiative energy transfer have been recognized. The net growth of the resonance Nd→Ce energy transfer rate in the temperature range from 25 to 55 K is found to be almost 3 orders of magnitude from 9.0×104 to 2.84×107 s−1. In a CeF3:Nd3+ (0.63 wt%) crystal a significant contribution of the Nd→Nd resonance energy transfer to the 4D3/2 manifold quenching is found for 20–40 K and its channel and mechanism are suggested. Discussion of the possibility of subpicosecond and picosecond nonradiative energy transfer in rare-earth doped laser crystals is provided.