Raman gain coefficient of Er³⁺ doped TeO₂–Li₂O–ZnO glasses

Tellurite glasses are good candidates for high-speed optical communications due to interesting properties and hence they present higher Raman cross section as compared to other glassy systems. In this work, tellurite glasses with 65TeO₂-15Li₂O-20ZnO (TLZ1) and 60TeO₂-15Li₂O-25ZnO (TLZ2) compositions and doped with different concentrations of Er₂O₃ (0.5; 1.0; and 2.0 mol%) were analyzed. The samples were synthetized by conventional melt-quenching method. The Raman gain coefficients of these glasses were obtained from Raman scattering experiments using 532 nm excitation. The Raman results presented a broad bandwidth from 225 to 1160 cm⁻¹ that become broader with Er³⁺ concentration. Besides that, a slight difference on the 760 cm⁻¹ band was observed with variation of the host composition. The Raman gain spectra presented a quenching effect for concentrations higher than 0.5 mol% and 1.0 mol% of Er₂O₃ for TLZ1 and TLZ2, respectively. This quenching have been attributed to the variation in TeO_x units present in each composition. The Raman gain coefficient increased with Er³⁺ concentration and these values were two orders of magnitude higher than silicate glasses. Therefore, the materials studied present potential as new media for Raman amplifiers.