CROSS-RELAXATION AND UP-CONVERSION COEFFICIENTS OF THE MIDINFRARED TRANSITIONS OF PR3+LACL3

Short pulse laser-induced fluorescence experiments on the lowest-energ y electronic states (upsilon < 10(-4) cm(-1)) of trivalent praseodymiu m ions are reported. Crystals of lanthanum trichloride with a range of Pr3+ concentrations were examined. We compute cross relaxation and up conversion coefficients for the metastable energy levels using a stand ard rate equation analysis. The limitations of the rate equation appro ach are examined with a focus on the underlying dynamics of this rare- earth system. The implications of these results for laser emission in the 1.3-7.2 mu m spectral range are discussed. (C) 1997 American Insti tute of Physics.