Near-infrared luminescence in titanate-germanate glasses co-doped with Cr3+/Ln3+ (Ln=Tm or Ho)

Near-infrared luminescence in titanate-germanate glasses co-doped with Cr3+/Ln3+ (where Ln = Tm or Ho) have been investigated under different excitation wavelengths. Near-infrared emission spectra and their decays were analyzed for glass samples varying with TiO2 content. Several emission bands in the 950–1570 nm and 1570–2200 nm spectral ranges are observed for glass samples excited directly at 600 nm (Cr3+), which correspond to characteristic transitions of Cr3+ and Ln3+ (Ln = Tm, Ho) ions. It suggests that the energy transfer processes Cr3+ → Tm3+ and Cr3+ → Ho3+ occur. It was also confirmed by the excitation spectra measurements. The experimental results indicate that titanate-germanate glasses co-doped with Cr3+/Ln3+ (Ln = Tm or Ho) are promising for near-infrared luminescence applications.