Dependence of spontaneous emission and nonradiative relaxations of Tm3+ and Er3+ on glass host and temperature

Abstract

Radiative transition probabilities from 3P0, 1I6, 1D2, and 1G4 levels of Tm3+ in glasses were calculated using the matrix elements obtained by intermediate coupling scheme and experimentally obtained intensity parameters. In the absence of self-absorption of fluorescence by the glass host, the fluorescence intensities of Tm3+ and Er3+ increase in the order borate < phosphate < germanate < tellurite. Nonradiative transition probabilities in different glass hosts from 1D2 to 1G4 levels of Tm3+ and from 4S3/2 to 4F9/2 and from 4F9/2 to 4I9/2 levels of Er3+ were calculated. The nonradiative transition rates follow the formula WNR = W (0) exp(−αp), where p is the number of phonons matching the energy gap. The nonradiative transition rates of Er3+ exhibit temperature dependence consistent with the multiphonon relaxation theory. In Tm3+ the temperature dependence of nonradiative relaxation rates is complicated by the existence of self-absorption and transfer of energy from matrix to Tm3+. Based on the above results, quantum efficiencies of luminescence of rare earth in glasses can be predicted.