Optical Spectroscopy of Nd3+ Centres in the Glass with 3CaO-Ga2O3-3GeO2 Composition

Optical absorption and luminescence spectra of Nd-doped glasses (0.2 and 1.0 wt. % of Nd2O3) with 3CaO-Ga2O3-3GeO2 (or Ca3Ga2Ge3O12 garnet) compositions are for the first time investigated in the temperature range of 4.2 - 300 K. EPR and optical spectroscopies have shown that the neodymium impurity is incorporated into the glass network exclusively as Nd3+ ions (the electron configuration 4f3 and the free-ion ground state 4I9/2). All the transitions of Nd3+ ions observed in the optical spectra are identified. The optical spectra of Nd3+ are analyzed with the standard Judd–Ofelt theory. The oscillator strengths, the intensity parameters W2, W4 and W6, the radiative emission probabilities, branching ratios and the radiative lifetime for Nd3+ ions in the glass with 3CaO-Ga2O3-3GeO2 composition are thus calculated. The luminescence kinetics of Nd3+ centres for 4F3/2 --> 4I11/2 transition at the room temperature could be satisfactorily described by exponential decay with the lifetimes 342 and 290 us for the samples containing respectively 0.2 and 1.0 wt. % of Nd2O3. The incorporation peculiarities, spectroscopic parameters and the local structure of luminescence Nd3+ centres in the glass with 3CaO-Ga2O3-3GeO2 composition are compared with those of the corresponding Ca3Ga2Ge3O12 garnet crystal.