Optical properties of Nd3+ -doped phosphate glasses have been studied on the basis of the Judd-Ofelt theory. With the intermediate cross-section value and the weak 4 / 6 parameter, we expect a relatively prominent 4 F3/2 4 I11/2 laser emission. The quenching effect of the emission intensity is discussed in terms of cross-relaxation between the Nd3+ ions as well as energy transfer processes within the host matrix. From the investigation of the decay rate from the 4 F3/2 state with the neodymium concentration, we suggest that self-quenching is insured by dipole-dipole interaction. This result was also confirmed by the simulation of the decay with the Inokuti-Hyrayama model.

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Emission spectroscopy of Cr3+‐doped phosphate glasses has been studied. Different site distributions of the chromium ions having an environment with nearly octahedral symmetry could be identified on the basis of the luminescence decay characteristics and the time‐resolved emission study. The low quantum yield in luminescence is attributed to an efficient multiphonon relaxation process deexciting rapidly ions submitted to the weaker crystal field.

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Raman scattering, optical absorption and photoluminescence studies have been performed on Er 3+ -doped Na 2 O-Nb 2 O 5 -GeO 2 germanate-based glasses. The main bands in the Raman spectra involve vibrational modes associated with the germanium oxide network. Judd -Ofelt intensity parameters were determined and then used to calculate the radiative transition rates and excited-state radiative lifetimes. Green and red up-conversion luminescence was observed at room temperature under 800 nm laser line excitation. The emission intensities have a quadratic dependence on the excitation pump power, indicating a two-step upconversion mechanism. The intensity of the 660 nm red band shows an increase relative to the 554 nm green band with increasing Er 3+ content. Combined with the time-resolved luminescence data of the emitting states, we suggest from these results that the up-conversion process is attributed to a competitive situation of excited-state absorption and energy transfer between excited ions accompanied by multiphonon relaxation.