Measurement of the laser transition cross section of neodymium glasses

Measurements were made of the Einstein coefficients of the spontaneous transitions from the ⁴F_3/2 metastable level of Nd³⁺ to all the levels of the ⁴I ground-state multiple occurring in several silicate and phosphate glasses. The cross sections of the ⁴F_3/2→⁴I_11/2 laser transition were determined. It was demonstrated that the spectroscopic methods suggested in the literature for the determination of these quantities could give rise to basic and uncontrollable errors.