Α method which takes into account normalized oscillator strengths is detailed for the calculation of parameters in Judd-Ofelt theory (B.R. Judd, Phys. Rev. 127, 750 (1962), G.S. Ofelt, J. Chem. Phys. 37, 511 (1962) Solidi B 157, 267 (1990)) are also considered but do not improve the calculated intensities when the energy of the 5d level is set to its experimentally determined value. Finally, in connection with 1.3 μm amplification, the 1.3 hn1 reabsorption ( 1i.4 → 1D2) oscillator strength is computed from the various models as well as the 1.3 /im emission branching ratio ( 1G4 --> 3H5/ 1G4 -3H6). The best agreement with experiment is obtained with the standard Judd-Ofelt theory.