Compositional dependence of nonradiative decay rate in Nd laser glasses

Abstract

Variations of nonradiative decay rate from 4 F 3 2 of a neodymium ion with the change of network modifier were determined from the fluorescence lifetime and radiative decay rate, calculated on the basis of Judd-Ofelt theory, for silicate and phosphate glasses. While, on the basis of Miyakawa-Dexter's theory, the nonradiative decay rate due to the multiphonon relaxation process was estimated from the electron-phonon coupling strength and phonon energy which were in turn determined from phonon sideband measurements. The latter did not always give the same modifier dependence of the nonradiative decay rate as the former, which suggested that the Judd-Ofelt theory did not always give the precise value of the radiative decay rate. The opposite variations of nonradiative decay rate with alkali modifier were found for silicate and phosphate glasses. This was explained as a result of the difference in the contribution of the electron-phonon coupling strength to the nonradiative decay rate due to the multiphonon relaxation process.