Red-emitting Type Fiber-adaptive Rare-earth Doped Germanotellurite Glasses

Rare earth doped glasses are important optical materials, which can be used to fabricate photonic devices such as optical fiber and waveguide for optical communication, lasers, 3D display and photodynamic therapy(PDT) light sources etc. Fiber sources hold great promise to develop PDT light sources due to some advantages over traditional laser and LED light sources.This project reports the preparation of Sm3+/Eu3+ doped germanotellurite glasses and their properties such as thermal stability, phonon energy, Judd-Ofelt(J-O) intensity parameters, spectroscopy and external quantum yield are characterized. The results are as follows:1. According to the molar host composition 14Na2O?10ZnO?7PbO?19GeO2?50TeO2(NZPGT), Sm3+/Eu3+ doped NZPGT glasses were prepared from high-purity Na2CO3, ZnO, PbO, GeO2, and TeO2 powders by traditional melt-quenching method. Additional Sm2O3(0.2wt% and 0.4wt%) and Eu2O3(0.2wt% and 1.2wt%) were introduced into the NZPGT glass composition based on the host weight. The thermal stability range is 101°C, indicating that high quality optical fiber can be drawn from the glass host.2. Based on J-O theory, J-O intensity parameters of Sm3+/Eu3+ in NZPGT glasses were deduced from absorption/emission spectrum. The ?t(t=2,4,6)of Sm3 + in NZPGT glasses are 3.52?10?20,4.70?10?20 and 1.90?10?20 cm2;The ?t(t=2,4)of Eu3 + in NZPGT glasses are 6.25?10?20 and 1.77?10?20 cm2, which indicates a high asymmetrical and covalent environment around Sm3+/Eu3+ in the optical glasses. The oscillator strengths, calculated radiative lifetime Ï„rad and fluorescence branching ratios βij were calculated from J-O intensity parameters. The maximum stimulated emission cross-section of the dominant transition 4G5/2?6H9/2 of Sm3+ was derived to be 10.00×10-22 cm2; the maximum stimulated emission cross-section of the dominant transition 5D0â†'7F2 of Eu3+ were derived to be 2.05×10-21 cm2.3. The external quantum yields of 0.4wt% Sm2O3 and 1.2wt% Eu2O3 doped NZPGT glasses were measured to be 6.0% and 4.0% respectively under 456 nm LED excitation; the external quantum yields of 1.2wt% Eu2O3 doped NZPGT glasses were measured to be 12% under 391 nm LED excitation using fiber spectrophotometer-integrating sphere system.This project indicates that Sm3+/Eu3+ doped NZPGT glasses possess good thermal stability, large maximum stimulated emission cross-sections and external quantum yields, which lays theoretical and experimental foundation for developing red fluorescence fiber sources for PDT.