Effect of Point Defects on Laser Oscillation Properties of Nd-Doped Y2O3

Some laser oscillation parameters of Nd-doped Y2O3 for the 4F3/2→4I11/2 transition are discussed in terms of the point defect concentration. The defect concentration was examined by measuring the electrical conductivities at 1450°C under various oxygen pressures, and the composition of the specimen was controlled by annealing at that temperature in an appropriate oxygen pressure. The laser oscillation loss of 0.50 at.% Nd-doped Y2O3 was minimum when the oxygen pressure during annealing was about 10-8 atm, where the rod was considered to attain the stoichiometric composition. The loss increased as the defect concentration increased. The absorption coefficient of undoped Y2O3 depended on the annealing atmosphere qualitatively in the same way as the loss. The effect of the oxygen pressure during annealing on the fluorescence lifetime was much smaller than that on the loss.