Novel erbium doped PbO and B2O3 based glasses with broad 1.5 μm absorption line width and low refractive index

Novel Er3+ doped PbO:B2O3, PbO:Ga2O3:B2O3, PbO:Bi2O3:B2O3 and PbO:Ga2O3:Bi2O3:B2O3 glasses showing very large absorption line width and low refractive index were prepared and characterized. The effective bandwidth Δλeff for such glasses varied from 63 to 92.6 nm and their refractive index ranged from 1.9383 to 1.6775. A Judd–Ofelt analysis was applied to these glasses and very high values were obtained (12.10 × 10−20 cm2), which are considered one factor responsible for the large Δλeff. The compositional dependence of was found to increase with increasing B2O3 content and with decreasing PbO content. Investigation of the Urbach energy (Eu) of host glasses was carried out and a correlation between Δλeff and Eu was proposed, giving a further explanation for the broad 1.55 μm bandwidth. Chemical and physical properties (glass transition temperature, crystallization temperature, density and refractive index) were studied. The compositional dependence of refractive index and density was discussed: they were found to decrease with decreasing PbO content and increasing B2O3; Ga2O3 also contributed to decrease the refractive index besides increasing the thermal stabilities of glasses. All glasses showed good water durability: the best one was shown by glasses containing Bi2O3. Measured 1.55 μm emission spectra and lifetimes were also discussed.