Auger upconversion losses in Nd-doped laser glasses

Abstract We have measured the Auger upconversion constant, γ, of Nd 3+ ions in phosphate, silicate, and fluoride glasses. The Auger process involves two Nd 3+ ions initially in the 4 F 3 2 metastable state that interact such that one ion is promoted to a higher lying state, while the other is forced to the 4 I J levels of the ground state. γ values ranging from 2.6 to 8.1 × 10 -17 cm 3 s -1 were measured, depending on the host medium and neodymium concentration. The product of the emission lifetime and the Auger coefficient was found to be in the range of γτ = (1 − 2) × 10 -20 cm 3 for the materials investigated. This suggests that Auger upconversion is an important problem for excited state densities approaching (5 − 10) × 10 19 cm -3 .